KR20210036402A - Reference image management in video coding - Google Patents

Abstract

A method of decoding a coded video bitstream is provided. The method includes parsing a parameter set represented by the coded video bitstream. The parameter set includes a set of syntax elements including a set of reference picture list structures. The method also includes parsing a slice header of a current slice represented by the coded video bitstream. The slice header includes an index of a reference picture list structure in a reference picture list structure set in the parameter set. The method further includes deriving a reference picture list of the current slice based on the set of syntax elements in the parameter set and an index of the reference picture list structure. The method also includes obtaining one or more reconstructed blocks of the current slice based on the reference image list.

Description

Reference image management in video coding

Cross-reference to related applications

This patent application was filed on August 17, 2018 by Wang Ye-Kui et al. under the name "Reference Picture Management in Video Coding", U.S. Provisional Patent Application No. 62/719,360 Claiming the benefit of this patent application, the above application is incorporated by reference into this patent application.

This disclosure generally relates to techniques for reference picture management in video coding. More specifically, the present disclosure describes a technique for constructing a reference picture list and reference picture marking.

The amount of video data required to show even relatively short video can be significant, which can lead to difficulties when the data is streamed or communicated over a communication network with limited bandwidth capacity. Thus, video data is typically compressed before being communicated over modern telecommunication networks. Since memory resources may be limited, the size of the video may also be an issue when the video is stored in a storage device. Video compression devices often code video data prior to transmission or storage using software and/or hardware at the source, reducing the amount of data required to represent a digital video image. The compressed data is then received at a destination by a video decompression device that decodes the video data. As the demand for limited network resources and higher video quality continues to increase, improved compression and decompression techniques that improve compression ratios without sacrificing little or no image quality are desirable.

The first aspect relates to a method of decoding a coded video bitstream. The method includes parsing a parameter set represented by the coded video bitstream, the parameter set comprising a set of syntax elements comprising a set of reference picture list structures; Parsing a slice header of a current slice represented by the coded video bitstream, the slice header including an index of a reference picture list structure in a set of reference picture list structures in the parameter set; Deriving a reference picture list of the current slice based on the set of syntax elements in the parameter set and an index of the reference picture list structure; And obtaining one or more reconstructed blocks of the current slice based on the reference image list.

This method provides a technique for simplifying and more efficient signaling of a reference picture list. Thus, the entire coding process is improved.

In a first implementation form of the method according to the first aspect, the order of entries in the reference image list structure is the same as the order of corresponding reference images in the reference image list.

In the second implementation form of the method according to the first aspect or in any preceding implementation form of the first aspect, the order of the entries is from zero to the indicated value.

In a third implementation form of the method according to the first aspect or any preceding implementation form of the first aspect, the indicated value is from 0 to the value indicated by sps_max_dec_pic_buffering_minus1.

In a fourth implementation form of the method according to the first aspect or any preceding implementation form of the first aspect, the reference picture list is designated as RefPictList[0].

In the fifth implementation form of the method according to the first aspect or any preceding implementation form of the first aspect, the reference picture list is designated as RefPictList[1].

In a sixth implementation form of the method according to the first aspect or in any preceding implementation form of the first aspect, the one or more reconstructed blocks are used to generate an image to be displayed on the display of the electronic device.

In the seventh implementation form of the method according to the first aspect or any preceding implementation form of the first aspect, the reference picture list includes a list of reference pictures used for inter prediction.

In an eighth implementation form of the method according to the first aspect or any preceding implementation form of the first aspect, the inter prediction is for a P slice or a B slice.

In a ninth implementation form of the method according to the first aspect or any preceding implementation form of the first aspect, the parameter set comprises a sequence parameter set (SPS).

In the tenth implementation form of the method according to the first aspect or in any preceding implementation form of the first aspect, the set of syntax elements from the parameter set is a raw byte sequence payload of a Network Abstraction Layer (NAL) unit. Arranged in (Raw Byte Sequence Payload, RBSP).

In the eleventh implementation form of the method according to the first aspect or any preceding implementation form of the first aspect, the reference picture list is designated as RefPictList[0] or RefPictList[1], and the order of entries in the reference picture list structure Is the same as the order of the corresponding reference images in the reference image list.

In a twelfth implementation form of the method according to the first aspect or in any preceding implementation form of the first aspect, parsing a parameter set represented by the coded video bitstream, the parameter set being a set of reference picture list structures. Contains a set of containing syntax elements -; Obtaining a reference picture list structure represented by the coded video bitstream; Deriving a first reference picture list of the current slice based on the reference picture list structure-The first reference picture list includes one or more active entries and one or more inactive entries, and the one The above inactive entry refers to a reference picture that is not used for inter prediction of the current slice but is referenced by an active entry in a second reference picture list, and the second reference picture list includes a slice following the current slice in decoding order. It is a reference picture list or a reference picture list of the picture following the current picture in decoding order -; And obtaining one or more reconstructed blocks of the current slice based on one or more active entries of the first reference image list.

A second aspect relates to a decoding device, the decoding device comprising: a receiver configured to receive a coded video bitstream; A memory coupled to the receiver and storing instructions; And a processor coupled to the memory, wherein the processor executes an instruction stored in the memory to parse a parameter set represented by the coded video bitstream, the parameter set comprising a set of reference picture list structures. Contains a set of syntax elements that do -; Parsing a slice header of a current slice represented by the coded video bitstream, the slice header including an index of a reference picture list structure in a set of reference picture list structures in the parameter set; Derive a reference picture list of the current slice based on the set of syntax elements in the parameter set and the index of the reference picture list structure; Based on the reference image list, it is configured to obtain one or more reconstructed blocks of the current slice.

The decoding device provides a technique for simplifying and more efficient signaling of a reference video list. Thus, the entire coding process is improved.

In a first implementation form of the decoding device according to the second aspect, the decoding device further includes a display configured to display a current image generated based on the one or more reconstructed blocks.

A third aspect relates to a coding apparatus comprising: a receiver configured to receive a bitstream to be decoded; A transmitter coupled to the receiver and configured to transmit a decoded image to a display; A memory coupled to at least one of the receiver or the transmitter and configured to store instructions; And a processor coupled to the memory and configured to execute an instruction stored in the memory to perform the method in any of the preceding aspects or implementation forms.

In a fourth aspect, the system comprises: an encoder; And a decoder in communication with the encoder. The encoder or decoder comprises a decoding device or a coding device in any of the preceding aspects or implementation forms.

The system provides a technique for simplifying and more efficient signaling of a reference picture list. Thus, the entire coding process is improved.

A fifth aspect relates to means for coding, the means for coding comprising: receiving means configured to receive a bitstream to be decoded; Transmitting means coupled to the receiving means and configured to transmit the decoded image to the display means; Storage means coupled to at least one of said receiving means or said transmitting means and configured to store an instruction; And processing means coupled to said storage means and configured to execute instructions stored in said storage means to perform the method in any of the preceding aspects or implementation forms.

This means for coding provides a technique that simplifies and makes the signaling of the reference picture list more efficient. Thus, the entire coding process is improved.

For a more complete understanding of the present disclosure, reference is made to the following brief description taken in connection with the accompanying drawings and detailed description, where like reference numerals designate like parts.
1 is a block diagram illustrating an exemplary coding system capable of using a bi-lateral prediction technique.
2 is a block diagram illustrating an exemplary video encoder capable of implementing a bilateral prediction technique.
3 is a block diagram showing an example of a video decoder capable of implementing a bilateral prediction technique.
4 is a schematic diagram showing an RPS having a picture having entries in all subsets of a reference picture set (RPS).
5 is an embodiment of a method of decoding a coded video bitstream.
6 is a schematic diagram of a video coding device.
7 is a schematic diagram of an embodiment of a means for coding.

1 is a block diagram illustrating an exemplary coding system 10 that may utilize video coding techniques as described herein. As shown in FIG. 1, the coding system 10 includes a source device 12 that provides encoded video data to be decoded later by a destination device 14. In particular, the source device 12 may provide video data to the destination device 14 through a computer-readable medium 16. Source device 12 and destination device 14 are desktop computers, notebook computers (e.g. laptop) computers, tablet computers, set-top boxes, telephone handsets such as so-called "smart" phones, so-called "smart" pads, televisions, cameras, displays. Devices, digital media players, video gaming consoles, video streaming devices, and the like. In some cases, the source device 12 and the destination device 14 may be equipped for wireless communication.

Destination device 14 may receive encoded video data to be decoded via computer-readable medium 16. Computer-readable medium 16 may include any tangible medium or device capable of moving encoded video data from source device 12 to destination device 14. In one example, the computer-readable medium 16 may comprise a communication medium that enables the source device 12 to transmit the encoded video data directly to the destination device 14 in real time. The encoded video data may be modulated and transmitted to the destination device 14 according to a communication standard, such as a wireless communication protocol. The communication medium may include any wireless or wired communication medium, such as a radio frequency (RF) spectrum or one or more physical transmission lines. Alternatively, the communication medium may form part of a packet-based network, such as a local area network, a wide area network, or a global network such as the Internet. Communication media may include routers, exchanges, base stations, or any other equipment that may be useful to facilitate communication from source device 12 to destination device 14.

In some examples, the encoded data may be output from the output interface 22 to a storage device. Similarly, encoded data can be accessed from a storage device by an input interface. Storage devices include hard drives, Blu-ray discs, digital video disks (DVDs), Compact Disc Read-Only Memory (CD-ROM), flash memory, volatile or non-volatile memory. It may include any of a variety of distributed or locally accessed data storage media, such as volatile memory or other suitable digital storage media for storing encoded video data. In a further example, the storage device may correspond to a file server or other intermediate storage device capable of storing the encoded video generated by the source device 12. The destination device 14 may access the stored video data from the storage device via streaming or download. The file server may be any type of server capable of storing encoded video data and transmitting the encoded video data to destination device 14. Exemplary file servers include web servers (eg, for web sites), file transfer protocol (FTP) servers, Network Attached Storage (NAS) devices, or local disk drives. Destination device 14 may access the encoded video data through any standard data connection, including an Internet connection. This includes a wireless channel (e.g. Wi-Fi connection), a wired connection (e.g. digital subscriber line (DSL), cable modem, etc.), or a combination of the two suitable for accessing encoded video data stored on a file server. Can be included. The transmission of the encoded video data from the storage device may be a streaming transmission, a download transmission, or a combination thereof.

The techniques of this disclosure are not necessarily limited to wireless applications or settings. These technologies include over-the-air television broadcasting, cable television transmission, satellite television transmission, Internet streaming video transmission, such as dynamic adaptive streaming over HTTP (DASH), digital video encoded on data storage media, and data storage. It can be applied to video coding supporting any of a variety of multimedia applications, such as digital video stored on a medium, or other applications. In some examples, the coding system 10 may be configured to support one-way or two-way video transmission to support applications such as video streaming, video playback, video broadcasting, and/or video telephony.

In the example of FIG. 1, source device 12 includes a video source 18, a video encoder 20 and an output interface 22. The destination device 14 comprises an input interface 28, a video decoder 30 and a display device 32. According to the present disclosure, the video encoder 20 of the source device 12 and/or the video decoder 30 of the destination device 14 may be configured to apply a technique for video coding. In another example, the source device and the destination device may include other components or arrangements. For example, the source device 12 receives video data from an external video source, such as an external camera. Likewise, the destination device 14 does not include an integrated display device, but may interface with an external display device.

The illustrated coding system 10 of FIG. 1 is only one example. Video coding techniques can be performed by any digital video encoding and/or decoding device. Although the technique of this disclosure is generally performed by a video coding device, this technique may also be performed by a video encoder/decoder generally referred to as “CODEC”. Moreover, the techniques of this disclosure can also be performed by a video preprocessor. The video encoder and/or decoder may be a graphics processing unit (GPU) or similar device.

Source device 12 and destination device 14 are only examples of such coding devices in which the source device 12 generates coded video data for transmission to the destination device 14. In some examples, source device 12 and destination device 14 may each include a video encoding and decoding component so that source device 12 and destination device 14 can operate in a substantially symmetrical manner. Thus, the coding system 10 may support one-way or two-way video transmission between video devices 12, 14, for example, for video streaming, video playback, video broadcasting or video telephony.

The video source 18 of the source device 12 includes a video capture device such as a video camera, a video archive containing previously captured video, and/or a video feed interface for receiving video from a video content provider. (video feed interface) may be included. As a further alternative, video source 18 may generate computer graphics-based data as source video, or a combination of live video, archived video and computer-generated video.

In some cases, when the video source 18 is a video camera, the source device 12 and the destination device 14 may form a so-called camera phone or video phone. However, as described above, the techniques described in this disclosure can generally be applied to video coding and to wireless and/or wired applications. In each case, the captured, pre-captured, or computer-generated video may be encoded by the video encoder 20. The encoded video information may be output to a computer-readable medium 16 by an output interface 22.

The computer-readable medium 16 may be a transient media such as a wireless broadcast or wired network transmission, or a hard disk, a flash drive, a compact disk, a digital video disk, a Blu-ray disk, or other computer-readable medium. Storage media (ie, non-transitory storage media). In some examples, a network server (not shown) may receive encoded video data from source device 12 and provide the encoded video data to destination device 14, such as via network transmission. Similarly, a computing device in a media production facility, such as a disc stamping facility, may receive encoded video data from the source device 12 and generate a disc containing the encoded video data. Accordingly, the computer-readable medium 16 may be understood to include one or more computer-readable media of various types, in various examples.

The input interface 28 of the destination device 14 receives information from the computer-readable medium 16. The information on the computer-readable medium 16 includes syntax elements describing the characteristics and/or processing of blocks and other coded units, e.g., Group of Pictures (GOPs). , May contain syntax information defined by the video encoder 20, which is also used by the video decoder 30. The display device 32 displays the decoded video data to a user, and a cathode ray tube (CRT), a liquid crystal display (LCD), a plasma display, an organic light emitting diode (OLED) It may include any of a variety of display devices, such as a display or other type of display device.

The video encoder 20 and the video decoder 30 can operate according to video coding standards such as High Efficiency Video Coding (HEVC) standards currently being developed, and are based on the HEVC Test Model (HM). I can comply. Alternatively, the video encoder 20 and the video decoder 30 are alternatively referred to as Moving Picture Expert Group (MPEG)-4, Part 10, Advanced Video Coding (AVC), H.265/HEVC, or an extension of this standard. It can operate according to other proprietary or industry standards, such as the International Telecommunications Union Telecommunication Standardization Sector (ITU-T) H.264 standard. However, the technology of this disclosure is not limited to any specific coding standard. Other examples of video coding standards include MPEG-2 and ITU-T H.263. Although not shown in Fig. 1, in some aspects, video encoder 20 and video decoder 30 may be integrated with an audio encoder and decoder, respectively, and enable encoding of both audio and video of a common data stream or a separate data stream. For processing, it may include a suitable multiplexer-demultiplexer (MUX-DEMUX) unit, or other hardware and software. If applicable, the MUX-DEMUX device may conform to the ITU H.223 multiplexer protocol, or other protocols such as user datagram protocol (UDP).

Each of the video encoder 20 and the video decoder 30 includes at least one microprocessor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), and a field programmable gate array. array, FPGA), discrete logic, software, hardware, firmware, or combinations thereof. When the technology is partially implemented in software, the device may store instructions for the software in a suitable, non-transitory computer-readable medium and execute the instructions in hardware using one or more processors to perform the techniques of this disclosure. have. Each of the video encoder 20 and the video decoder 30 may be included in one or more encoders or decoders, any of which may be incorporated as part of a combined encoder/decod (CODEC) in each device. I can. Devices including video encoder 20 and/or video decoder 30 may include integrated circuits, microprocessors, and/or wireless communication devices such as cellular telephones.

2 is a block diagram showing an example of a video encoder 20 capable of implementing a video coding technique. The video encoder 20 may perform intra-coding and inter-coding of video blocks in a video slice. Intra coding relies on spatial prediction to reduce or remove spatial redundancy of video within a given video frame or image. Inter coding relies on temporal prediction to reduce or remove temporal redundancy in adjacent frames of a video sequence or in video within an image. The intra mode (I mode) may refer to any of several spatial based coding modes. Inter-modes such as uni-directional prediction (also known as uni prediction) (P mode) or bi-prediction (also known as bi-prediction, bi prediction) (B mode) refer to any of several time-based coding modes. I can.

As shown in Fig. 2, video encoder 20 receives a current video block within a video frame to be encoded. In the example of FIG. 2, the video encoder 20 includes a mode selection unit 40, a reference frame memory 64, a summer 50, a transform processing unit 52, a quantization unit 54, and an entropy coding unit 56. ). The mode selection unit 40, in turn, includes a motion compensation unit 44, a motion estimation unit 42, an intra-prediction (also known as intra prediction) unit 46, and a segmentation unit 48. . For video block reconstruction, the video encoder 20 also includes an inverse quantization unit 58, an inverse transform unit 60 and a summer 62. A deblocking filter (not shown in FIG. 2) may also be included to filter the block boundaries to remove blockiness artifacts from the reconstructed video. If desired, the deblocking filter generally filters the output of summer 62. In addition to the deblocking filter, additional filters (in the loop or after the loop) can also be used. Such a filter is not shown for brevity, but if desired, the output of summer 50 can be filtered (as a filter in the loop).

During the encoding process, video encoder 20 receives a video frame or slice to be coded. A frame or slice can be divided into multiple video blocks. The motion estimation unit 42 and the motion compensation unit 44 provide temporal prediction by performing inter prediction coding of a video block received on one or more blocks in one or more reference frames. The intra prediction unit 46 may alternatively provide spatial prediction by performing intra prediction coding of a video block received on one or more neighboring blocks in the same frame or slice as the block to be coded. Video encoder 20 may perform multiple coding passes, for example to select an appropriate coding mode for each block of video data.

Moreover, the dividing unit 48 may divide the block of video data into sub-blocks based on the evaluation of the previous dividing scheme in the previous coding pass. For example, the partitioning unit 48 initially divides a frame or slice into a largest coding unit (LCU), and divides each LCU into a sub-coding unit based on rate distortion analysis (e.g., rate distortion optimization). It can be divided into (sub-coding unit, sub-CU). The mode selection unit 40 may further generate a quad-tree data structure indicating dividing the LCU into sub-CUs. A leaf-node CU of a quad tree may include one or more prediction units (PUs) and one or more transform units (TUs).

The present disclosure refers to the term “block” to refer to any of CU, PU or TU in the context of HEVC, or similar data structures (eg, macro blocks and sub-blocks thereof in H.264/AVC) in the context of other standards. Use. The CU includes a coding node, a PU, and a TU associated with the coding node. The size of the CU corresponds to the size of the coding node and has a square shape. The size of the CU can range from 8×8 pixels to a maximum tree block size of 64×64 pixels or more. Each CU may include one or more PUs and one or more TUs. Syntax data associated with the CU may describe, for example, dividing the CU into one or more PUs.

The partitioning mode may differ depending on whether the CU is encoded in a skip or direct mode, an intra prediction mode, or an inter prediction (also known as inter-prediction, inter prediction) mode. PU can be divided into non-square shapes. Syntax data associated with the CU may also describe dividing the CU into one or more TUs according to, for example, a quad tree. The shape of the TU may or may not be square (eg, rectangle).

The mode selection unit 40 may select one of an intra or inter coding mode based on, for example, an error result, and provides the resulting intra or inter-coded block to the summer 50 to generate residual block data, and Provided to summer 62 to reconstruct the encoded block for use as a reference frame. The mode selection unit 40 also provides syntax elements to the entropy coding unit 56, such as motion vectors, intra mode indicators, segmentation information and other such syntax information.

The motion estimation unit 42 and the motion compensation unit 44 can be highly integrated, but are shown separately for conceptual purposes. Motion estimation performed by the motion estimation unit 42 is a process of generating a motion vector that estimates motion for a video block. For example, the motion vector is the PU of the video block in the current video frame for the prediction block in the reference frame (or other coded unit) for the current block being coded in the current frame (or other coded unit). The displacement of can be indicated. The prediction block is compared to the block to be coded in terms of pixel differences, which can be determined by the sum of absolute difference (SAD), sum of square difference (SSD) or other difference metric. Blocks that have been confirmed to be closely matched. In some examples, the video encoder 20 may calculate a value for a sub-integer pixel position of the reference image stored in the reference frame memory 64. For example, the video encoder 20 may interpolate a value of a 1/4 pixel position, a 1/8 pixel position, or other partial pixel position of a reference image. Accordingly, the motion estimation unit 42 may perform a motion search for a complete pixel position and a partial pixel position, and output a motion vector with partial pixel precision.

The motion estimation unit 42 calculates a motion vector for the PU of the video block in the inter-coded slice by comparing the position of the PU with the position of the prediction block of the reference picture. The reference image may be selected from the first reference image list (List 0) or the second reference image list (List 1), each of which enables one or more reference images stored in the reference frame memory 64 to be identified. The motion estimation unit 42 transmits the calculated motion vector to the entropy encoding unit 56 and the motion compensation unit 44.

Motion compensation performed by the motion compensation unit 44 may include fetching or generating a prediction block based on a motion vector determined by the motion estimation unit 42. Further, in some examples, the motion estimation unit 42 and the motion compensation unit 44 may be functionally integrated. Upon receiving the motion vector for the PU of the current video block, the motion compensation unit 44 may find a prediction block indicated by the motion vector from one of the reference picture lists. The summer 50 forms a residual video block by subtracting the pixel value of the prediction block from the pixel value of the current video block being coded to form a pixel difference value as discussed below. In general, the motion estimation unit 42 performs motion estimation on a luma component, and the motion compensation unit 44 is calculated based on a luma component for both a chroma component and a luma component. Use a motion vector. The mode selection unit 40 may also generate the video block and syntax elements associated with the video slice for use by the video decoder 30 when decoding the video block of the video slice.

As described above, the intra prediction unit 46 may intra-predict the current block as an alternative to inter prediction performed by the motion estimation unit 42 and the motion compensation unit 44. In particular, the intra prediction unit 46 may determine an intra prediction mode to be used to encode the current block. In some examples, intra prediction unit 46 may encode the current block using various intra prediction modes, e.g., during a separate encoding pass, and intra prediction unit 46 (or mode selection unit 40 in some examples). ) Can select an appropriate intra prediction mode to be used among the tested modes.

For example, the intra prediction unit 46 may calculate a rate distortion value using rate distortion analysis for various tested intra prediction modes, and select an intra prediction mode having the best rate distortion characteristic among the tested modes. . Rate distortion analysis generally refers to the amount of distortion (or error) between the encoded block and the original unencoded block encoded to produce the encoded block, and the bit rate (i.e., the number of bits) used to generate the encoded block. ) Is determined. Intra prediction unit 46 can calculate a ratio from the rates and distortions for the various encoded blocks to determine which intra prediction mode represents the best rate distortion value for the block.

In addition, the intra prediction unit 46 may be configured to code a depth block of a depth map using a depth modeling mode (DMM). The mode selection unit 40 may determine whether the available DMM mode produces a better coding result than the intra prediction mode and other DMM modes, e.g., using rate-distortion optimization (RDO). Data on a texture image corresponding to the depth map may be stored in the reference frame memory 64. The motion estimation unit 42 and the motion compensation unit 44 may also be configured to inter-predict the depth block of the depth map.

After selecting an intra prediction mode for a block (eg, one of a conventional intra prediction mode or a DMM mode), the intra prediction unit 46 transmits information indicating the selected intra prediction mode for the block to the entropy coding unit 56 Can be provided to. The entropy coding unit 56 may encode information indicating the selected intra prediction mode. The video encoder 20 may include a plurality of intra prediction mode index tables and a plurality of modified intra prediction mode index tables (also referred to as codeword mapping tables) in the transmitted bitstream configuration data, encoding context of various blocks. And an indication of an intra prediction mode most likely to be used in each context, an intra prediction mode index table, and a modified intra prediction mode index table.

The video encoder 20 forms a residual video block by subtracting the prediction data from the mode selection unit 40 from the original video block being coded. Summer 50 represents a component that performs this subtraction operation.

The transform processing unit 52 generates a video block including a residual transform coefficient value by applying a transform such as a discrete cosine transform (DCT) or a conceptually similar transform to the residual block. The transform processing unit 52 may conceptually perform other transforms similar to DCT. Wavelet transforms, integer transforms, subband transforms or other types of transforms can also be used.

The transform processing unit 52 applies a transform to the residual block to generate a block of residual transform coefficients. Transformation may convert residual information from a pixel value domain to a transform domain such as a frequency domain. The transform processing unit 52 can transmit the resulting transform coefficient to the quantization unit 54. The quantization unit 54 quantizes the transform coefficients to further reduce the bit rate. The quantization process can reduce the bit depth associated with some or all of the coefficients. The degree of quantization can be modified by adjusting the quantization parameters. In some examples, quantization unit 54 may then perform a scan of the matrix including the quantized transform coefficients. Alternatively, the entropy encoding unit 56 can perform the scan.

Following quantization, the entropy coding unit 56 entropy codes the quantized transform coefficients. For example, the entropy coding unit 56 includes context adaptive binary arithmetic coding (CAVLC), context adaptive binary arithmetic coding (CABAC), and syntax-based context adaptive binary arithmetic. Coding (syntax-based context-adaptive binary arithmetic coding (SBAC)), probability interval partitioning entropy (PIPE) coding, or other entropy coding techniques may be performed. In the case of context-based entropy coding, the context may be based on a neighboring block. Following entropy coding by entropy coding unit 56, the encoded bitstream may be transmitted to another device (eg, video decoder 30) or stored for later transmission or retrieval.

The inverse quantization unit 58 and the inverse transform unit 60 apply inverse quantization and inverse transform, respectively, to reconstruct the residual block in the pixel domain for use as a reference block later, for example. The motion compensation unit 44 may calculate a reference block by adding a residual block to one of the frames of the reference frame memory 64. The motion compensation unit 44 may also apply one or more interpolation filters to the reconstructed residual block to calculate a sub-integer pixel value to be used for motion estimation. The summer 62 generates a reconstructed video block for storage in the reference frame memory 64 by adding the reconstructed residual block to the motion compensated prediction block generated by the motion compensation unit 44. The reconstructed video block is used by the motion estimation unit 42 and the motion compensation unit 44 as a reference block for inter-coding the block in a subsequent video frame.

3 is a block diagram showing an example of a video decoder 30 that can implement a video coding technique. In the example of FIG. 3, the video decoder 30 includes an entropy decoding unit 70, a motion compensation unit 72, an intra prediction unit 74, an inverse quantization unit 76, an inverse transform unit 78, and a reference frame memory ( 82) and a summer 80. Video decoder 30, in some examples, performs a decoding pass that is generally inverse to the encoding pass described for video encoder 20 (FIG. 2). The motion compensation unit 72 may generate prediction data based on the motion vector received from the entropy decoding unit 70, while the intra prediction unit 74 is an intra prediction mode indicator received from the entropy decoding unit 70. Prediction data may be generated based on.

During the decoding process, video decoder 30 receives from video encoder 20 an encoded video bitstream representing a video block of an encoded video slice and an associated syntax element. The entropy decoding unit 70 of the video decoder 30 entropy decodes the bitstream to generate quantized coefficients, motion vectors or intra prediction mode indicators, and other syntax elements. The entropy decoding unit 70 forwards the motion vector and other syntax elements to the motion compensation unit 72. The video decoder 30 may receive a syntax element at a video slice level and/or a video block level.

When a video slice is coded with an intra coded (I) slice, the intra prediction unit 74 determines the video of the current video slice based on the signaled intra prediction mode and data from a previously decoded block of the current frame or image. It is possible to generate predictive data for a block. When a video frame is coded as an inter-coded (e.g., B, P or GPB) slice, the motion compensation unit 72 determines the current video slice based on the motion vector and other syntax elements received from the entropy decoding unit 70. Generate a prediction block for a video block. The prediction block may be generated from one of the reference pictures in one of the reference picture lists. The video decoder 30 may construct a reference frame list, list 0 and list 1 by using a default construction technique based on a reference image stored in the reference frame memory 82.

The motion compensation unit 72 determines prediction information for a video block of a current video slice by parsing a motion vector and other syntax elements, and generates a prediction block for the current video block to be decoded using the prediction information. For example, the motion compensation unit 72 uses some of the received syntax elements, a prediction mode (e.g., intra prediction or inter prediction) used to code a video block of a video slice, and an inter prediction slice type (e.g. : B slice, P slice, or GPB slice), construction information for one or more of the reference image list for the slice, motion vector for each inter-encoded video block of the slice, inter prediction for each inter-coded video block of the slice Determine the state, and other information for decoding the video block in the current video slice.

The motion compensation unit 72 may also perform interpolation based on an interpolation filter. The motion compensation unit 72 may use an interpolation filter used by the video encoder 20 during encoding of the video block to calculate interpolated values for less than integer pixels of the reference block. In this case, the motion compensation unit 72 may determine an interpolation filter used by the video encoder 20 from the received syntax element and use the interpolation filter to generate a prediction block.

Data on the texture image corresponding to the depth map may be stored in the reference frame memory 82. The motion compensation unit 72 may also be configured to inter-predict the depth block of the depth map.

Image and video compression has experienced rapid growth and has led to a variety of coding standards. Such video coding standards include ITU-T H.261, ISO/IEC Motion Picture Experts Group (MPEG)-1 Part 2, ITU-T H.262, or International Organization for Standardization (ISO)/International Electrotechnical Commission (IEC) MPEG. -Advanced Video Coding (AVC), H.265 or also known as 2 Part 2, ITU-T H.263, ISO/IEC MPEG-4 Part 2, ITU-T H.264 or ISO/IEC MPEG-4 Part 10 It includes High Efficiency Video Coding (HEVC), also known as MPEG-H Part 2. AVC includes extensions such as Scalable Video Coding (SVC), Multiview Video Coding (MVC), Multiview Video Coding plus Depth (MVC+D), and 3D-AVC (3D AVC). HEVC includes extensions such as Scalable HEVC (SHVC), Multiview HEVC (MV-HEVC) and 3D HEVC (3D HEVC).

Versatile Video Coding (VVC) is a new video coding standard being developed by the joint video experts team (JVET) of ITU-T and ISO/IEC. At the time of writing, VVC's latest Working Draft (WD) is included in JVET-K1001-v1. The JVET document JVET-K0325-v3 contains an update to the advanced syntax of VVC.

In general, this disclosure describes the technology under development of the VVC standard. However, this technique also applies to other video/media codec specifications.

Video compression technology performs spatial (intra image) prediction and/or temporal (inter image) prediction in order to reduce or remove redundancy inherent in a video sequence. In the case of block-based video coding, a video slice (eg, a video image or a part of a video image) may be divided into video blocks, which are tree blocks, coding tree blocks (CTBs), coding tree units (CTUs), and coding units ( CU) and/or a coding node. The video blocks of the intra-coded (I) slice of the picture are encoded using spatial prediction for reference samples in neighboring blocks of the same picture. A video block of an inter-coded (P or B) slice of an image may use spatial prediction for a reference sample of a neighboring block of the same image or temporal prediction for a reference sample of another reference image. An image may be referred to as a frame, and a reference image may be referred to as a reference frame.

Spatial prediction or temporal prediction produces as a result a prediction block for the block to be coded. The residual data represents a pixel difference between an original block to be coded and a prediction block. The inter-coded block is encoded according to a motion vector indicating a reference sample block forming a prediction block and residual data indicating a difference between the coded block and the prediction block. The intra coded block is encoded according to the intra coding mode and residual data. For further compression, the residual data can be transformed from the pixel domain to the transform domain, and as a result residual transform coefficients can be generated, which can be quantized later. Quantized transform coefficients initially arranged in a two-dimensional array can be scanned to generate a one-dimensional vector of transform coefficients, and entropy coding can be applied to achieve even more compression.

In the video codec specification, an image includes for use as a reference image in inter prediction, for outputting an image from a decoded image buffer (DPB), for scaling motion vectors, for weighted prediction, etc. , Identified for several purposes. In AVC and HEVC, an image can be identified by a picture order count (POC). In AVC and HEVC, the image of the DPB may be marked as "used for short-term reference", "used for long-term reference" or "not used for reference". If an image is marked "not used for reference", the image can no longer be used for prediction. If the image is no longer needed for output, the image can be removed from the DPB.

In AVC, there are two types of reference images, short and long. If the reference image is no longer needed for predictive reference, it may be marked as "not used for reference". The transformation between these three states (short term, long term and not used for reference) is controlled by the decoded reference image marking process. There are two alternative decoded reference picture display mechanisms: an implicit sliding window process and an explicit memory management control operation (MMCO) process. The sliding window process marks a short-term reference image as "not used for reference" when the number of reference frames is equal to a given maximum number (max_num_ref_frames of the sequence parameter set (SPS)). The short-term reference image is stored in a first-in, first-out manner, and the most recently decoded short-term image is stored in the DPB.

The explicit MMCO process can include multiple MMCO commands. The MMCO command can mark one or more short or long-term reference images as "not used for reference", or all images as "not used for reference", or a current reference image or an existing short-term reference After the images are marked as organs, a long-term reference image index is assigned to the long-term reference image.

In AVC, after an image is decoded, a process for outputting and removing an image from a DPB as well as a reference image marking operation is performed.

HEVC introduces a different approach for reference picture management, called a reference picture set (RPS). The most fundamental difference of the RPS concept compared to AVC's MMCO/sliding window process is that for each particular slice a complete set of reference pictures used by the current picture or any subsequent picture is provided. Thus, a complete set of all images that must be kept in the DPB for use by current or future images is provided. This is different from the AVC scheme, which signals only relative changes to the DPB. Using the RPS concept, information from the previous picture is not required in the decoding order in order to maintain the correct state of the reference picture in the DPB.

In HEVC, the order of video decoding and DPB operations is changed in order to utilize the advantages of RPS compared to AVC and improve error resilience. In AVC, picture marking and buffer manipulation (both outputting and removing the decoded picture from the DPB) are generally applied after the current picture is decoded. In HEVC, the RPS is first decoded from the slice header of the current picture, and then picture marking and buffer manipulation are generally applied before decoding the current picture.

In HEVC, each slice header must include a parameter for RPS signaling for a video including a slice. The only exception is that RPS is not signaled for Instantaneous Decoding Refresh (IDR) slices. Instead, it is assumed that the RPS is empty. In the case of an I slice that does not belong to an IDR image, even if it does not belong to an I image, since there may be an image following the I image in decoding order using inter prediction from the image preceding the I image in decoding order, an RPS may be provided. . The number of images in the RPS must not exceed the DPB size limit specified by the sps_max_dec_pic_buffering syntax element in the SPS.

Each image is associated with a POC value indicating the output order. The slice header includes a fixed length codeword, pic_order_cnt_lsb, representing the least significant bit (LSB) of the entire POC value, also known as POC LSB. The length of the code word is signaled in the SPS, and may be between 4 bits and 16 bits, for example. The RPS concept identifies a reference image using POC. In addition to its own POC value, each slice header directly contains a coded representation of the POC value (or LSB) of each picture in the RPS or inherits from the SPS.

The RPS for each picture consists of five different lists of reference pictures, also referred to as a subset of the five RPS. RefPicSetStCurrBefore consists of all short-term reference images that precede the current image in both the decoding order and the output order, and can be used for inter prediction of the current image. RefPicSetStCurrAfter is composed of all short-term reference pictures that precede the current picture in decoding order, follow the current picture in output order, and can be used for inter prediction of the current picture. RefPicSetStFoll can be used for inter prediction of one or more pictures following the current picture in decoding order, and consists of all short-term reference pictures that are not used for inter prediction of the current picture. RefPicSetLtCurr consists of all long-term reference images that can be used for inter prediction of the current image. RefPicSetLtFoll can be used for inter prediction of one or more pictures following the current picture in decoding order, and consists of all long-term reference pictures that are not used for inter prediction of the current picture.

The RPS is signaled using different types of reference pictures: a short-term reference picture having a lower POC value than the current picture, a short-term reference picture having a higher POC value than the current picture, and a maximum of three loops repeated through the long-term reference picture.

In addition, a flag indicating whether the reference image is used for reference by the current image (included in one of the lists RefPicSetStCurrBefore, RefPicSetStCurrAfter or RefPicSetLtCurr) or not (not included in one of the lists RefPicSetStFoll or RefPicSetLtFoll) (used_by_curr_pic_pic_pic) Is transmitted for each reference image.

4 shows an RPS 400 with a current picture B14 having an entry (eg, video) in all subsets 402 of the RPS 400. In the example of FIG. 4, the current picture B14 contains exactly one picture in each of the five subsets 402 (also known as the RPS subset). P8 is an image of a subset 402 called RefPicSetStCurrBefore because the image is ahead in the output order and is used by B14. P12 is an image of a subset 402 called RefPicSetStCurrAfter because the image is later in the output order and is used by B14. P13 is a picture of a subset 402 called RefPicSetStFoll because the picture is a short-term reference picture that is not used by B14 (but must be kept in DPB because it is used by B15). P4 is an image of a subset 402 called RefPicSetLtCurr because the image is a long-term reference image used by B14. I0 is an image of a subset 402 called RefPicSetLtFoll because the image is a long-term reference image that is not used by the current image (but must be maintained in the DPB because it is used by B15).

The short-term portion of the RPS 400 may be directly included in the slice header. Alternatively, the slice header may contain only a syntax element indicating an index, and refers to a predefined RPS list transmitted in the active SPS. The short-term portion of RPS 402 may be signaled using one of two different ways: Inter RPS described below or Intra RPS described herein. When intra RPS is used, num_negative_pics and num_positive_pics are signaled to indicate the lengths of two different reference picture lists. Each of these lists includes a reference image having a negative POC difference and a positive POC difference compared to the current image. Each of these list elements is encoded with a variable length code representing the difference in POC value associated with the previous element of the list minus one. For the first video in each list, signaling is related to a value subtracting 1 from the POC value of the current video.

When encoding the repetitive RPS in the sequence parameter set, an element of one RPS (eg, RPS 400) may be encoded by referring to another RPS already encoded in the sequence parameter set. This is called inter RPS. There is no error robustness problem associated with this method since all RPSs of the sequence parameter variable set are in the same network abstraction layer (NAL) unit. Inter RPS syntax uses the fact that the RPS of the current picture can be predicted from the RPS of the previously decoded picture. This is because all reference images of the current image must be reference images of the previous image or images that have been previously decoded. It is only necessary to indicate which of these images should be the reference image and which should be used for prediction of the current image. Thus, the syntax may include: an index pointing to the RPS to be used as a predictor, a delta_POC to be added to the delta_POC of the predictor to obtain the delta POC of the current RPS, and which image is the reference image and of the future image. A set of indicators that indicate whether they are used only for prediction.

An encoder that intends to use the long-term reference picture must set the SPS syntax element long_term_ref_pics_present_flag to 1. Then, the long-term reference picture may be signaled in the slice header by a fixed-length code word, poc_lsb_lt, indicating the least significant bit of the total POC value of each long-term picture. Each poc_lsb_lt is a copy of the pic_order_cnt_lsb codeword that was signaled for a specific organ image. It is also possible to signal the long-term image set of the SPS as a list of POC LSB values. The POC LSB for the long-term image can then be signaled as an index to this list in the slice header.

The delta_poc_msb_cycle_lt_minus1 syntax element may be additionally signaled to calculate the total POC distance of the long-term reference image with respect to the current image. The code word delta_poc_msb_cycle_lt_minus1 should be signaled for each long-term reference picture having the same POC LSB value as other reference pictures of the RPS.

In the case of reference image marking in HEVC, in general, a plurality of images will exist in the DPB before image decoding. Some of the images are available for prediction and are marked "used for reference". Other images are not available for prediction, but are waiting for output, so they are marked as "not used for reference". If the slice header has already been parsed, an image marking process is performed before the slice data is decoded. Images that are in the DPB and marked "used for reference" but not included in the RPS are marked "not used for reference". Images that are not in the DPB but included in the reference picture set are ignored when used_by_curr_pic_X_flag is equal to 0. However, when used_by_curr_pic_X_flag is equal to 1, this reference picture is for use in prediction in the current picture, but is omitted. Then unintended video loss is inferred and the decoder must take appropriate action.

After decoding the current picture, it is marked "used for short-term reference".

Next, construction of a reference video list in HEVC will be described. In HEVC, the term inter prediction is used to denote prediction derived from data elements (eg, sample values or motion vectors) of a reference picture other than the currently decoded picture. Like AVC, an image can be predicted from multiple reference images. Reference pictures used for inter prediction are organized into one or more reference picture lists. The reference index makes it possible to identify which of the reference pictures in the list should be used to generate the prediction signal.

A single reference image list, List 0, is used for the P slice, and two reference image lists, List 0 and List 1, are used for the B slice. Similar to AVC, construction of a reference picture list in HEVC involves initializing the reference picture list and modifying the reference picture list.

In AVC, the initialization process for List 0 is different from that for P slices (decoding order is used) and B slices (output order is used). In HEVC, the output order is used in both cases.

The reference picture list initialization generates default List 0 and List 1 (when the slice is a B slice) based on three RPS subsets: RefPicSetStCurrBefore, RefPicSetStCurrAfter, and RefPicSetLtCurr. Short-term videos with a fast (late) output are first inserted into List 0 (List 1) in ascending order of the current video's POC distance, and then List 0 with a short-term video with a slower (fast) output sequence in ascending order of the POC distance to the current video. After being inserted in (List 1), the organ image is inserted at the end. In terms of RPS, in the case of List 0, an entry of RefPicSetStCurrBefore is inserted into the initial list, followed by an entry of RefPicSetStCurrAfter. Thereafter, an entry of RefPicSetLtCurr is added, if available.

In HEVC, if the number of entries in the list is smaller than the target number of the active reference picture (signaled in the picture parameter set or slice header), the above process is repeated (the reference picture already added to the reference picture list is added again). If the number of entries is greater than the number of targets, the list is truncated.

After the reference image list is initialized, it can be modified so that the reference images for the current image can be arranged in an arbitrary order, and based on the reference image list modification command, one specific reference image appears at one or more positions in the list. Includes possible cases. When the flag indicating that there is a list modification is set to 1, a fixed number of commands (same as the target number of entries in the reference video list) is signaled, and each command inserts one entry for the reference video list. do. The reference picture is identified in the command by an index into the list of reference pictures for the current picture derived from RPS signaling. This is different from the reference picture list modification in H.264/AVC, where the picture is identified by picture number (derived from frame_num syntax element) or long-term reference picture index, e.g. exchanging the first two entries of the initial list ( swapping) or inserting one entry at the beginning of the initial list and shifting other entries may require fewer commands.

The reference picture list cannot include a reference picture having a larger TemporalId than the current picture. The HEVC bitstream may be composed of several temporal sub-layers. Each NAL unit belongs to a specific sub-layer indicated by TemporalId (same as temporal_id_plus1-1).

Reference image management is based directly on the reference image list. JCT-VC document JCTVC-G643 includes an approach that directly uses three reference picture lists: reference picture list 0, reference picture list 1, and idle reference picture list to manage the reference picture in the DPB, 1) in AVC The sliding window and MMCO process as well as the reference picture list initialization and modification process, or 2) in HEVC, avoids the need for a signaling and decoding process including a reference picture set as well as a reference picture list initialization and modification process.

There may be several problems with the approach to reference image management. The AVC approach includes a sliding window, an MMCO process, and a complex reference image list initialization and modification process. Moreover, the loss of an image may lead to a loss of the state of the DPB in the aspect that a certain image must have an image in the DPB for additional inter prediction reference purposes. There is no DPB state loss problem with the HEVC approach. However, the HEVC approach involves not only a complex reference picture set signaling and derivation process, but also a complex reference picture list initialization and modification process. In JCTVC-G643, to manage the reference picture in the DPB, the approach of using three reference picture lists: reference picture list 0, reference picture list 1, and idle reference picture list includes the following aspects: Re-reference three times. An image list, that is, an idle reference image list; Two-part coding of the "short-term" part, the POC difference and the ue(v) coded "long-term" part; TemporalId-based POC granularity for POC difference coding, two-part coding of the POC difference to determine the marking between "used for short-term reference" or "used for long-term reference";

A reference picture list subset description that activates the ability to designate a reference picture list by removing the reference picture list from the tail of a specific earlier reference picture list description; A reference picture list copy mode activated by the syntax element ref_pic_list_copy_flag; And reference image list description process. Each of the preceding aspects complicates the approach unnecessarily. In addition, the decoding process for the reference picture list in JCTVC-G643 is also complicated. Signaling of a long-term reference picture may require signaling of a POC cycle in a slice header. This is not efficient.

In order to solve the problems listed above, the solutions disclosed herein may be applied individually, and some of them may be applied in combination. 1) Reference image marking is directly based on two reference image lists, namely, reference image list 0 and reference image list 1. 1a) Information for deriving two reference picture lists is signaled based on a syntax element and a syntax structure in the SPS, PPS and/or slice header. 1b) Each of the two reference picture lists for the picture is explicitly signaled in the reference picture list structure. 1b.i) One or more reference picture list structures can be signaled in the SPS, and each can be referenced by an index from the slice header. 1b.ii) Each of the reference picture lists 0 and 1 may be directly signaled in the slice header. 2) Information for derivation of two reference picture lists is signaled for all types of slices, that is, B (double prediction) slice, P (single prediction) slice, and I (intra) slice. The term slice refers to a slice of HEVC or a collection of coding tree units such as the latest VVC WD; It can also refer to other collections of coding tree units, such as tiles in HEVC. 3) Two reference picture lists are created for all types of slices, that is, B, P and I slices. 4) The two reference image lists are built directly without using the reference image list initialization process and the reference image list modification process. 5) In each of the two reference picture lists, a reference picture that can be used for inter prediction of the current picture can be referenced only by a number of entries at the beginning of the list. Such entries are referred to as active entries in the list, and other entries are referred to as inactive entries in the list. Both the total number of entries and the number of active entries in the list can be derived. 6) The picture referenced in the inactive entry of the reference picture list cannot be referenced by another entry in the reference picture list or by an entry in another reference picture list. 7) Long-term reference images are identified only by a specific number of POC LSBs, where this number may be greater than the number of POC LSBs signaled in the slice header for derivation of the POC value, and this number is indicated by the SPS. 8) The reference picture list structure is signaled only in the slice header, both the short-term reference picture and the long-term reference picture are identified by the POC LSB, and a bit used to indicate the POC LSB signaled in the slice header to derive the POC value. It may be expressed as a number of bits different from the number, and the number of bits used to indicate the POC LSB for identifying the short-term reference image and the long-term reference image may be different. 9) The reference picture list structure is signaled only in the slice header, does not distinguish between a short-term reference picture and a long-term reference picture, all reference pictures are only named as reference pictures, and reference pictures are identified by their POC LSBs, and It is expressed as a number of bits different from the number of bits used to indicate the POC LSB signaled in the slice header for derivation.

A first embodiment of the present disclosure is provided. The description relates to the latest VVC WD. In this embodiment, two sets of reference picture list structures, one for each of reference picture list 0 and reference picture list 1, are signaled in the SPS.

Provides definitions for some of the terms used here. Intra Random Access Point (IRAP) video: A coded video in which each video coding layer (VCL) NAL unit has the same nal_unit_type as IRAP_NUT. Non-IRAP (non-IRAP) picture: A coded picture in which each VCL NAL unit has the same nal_unit_type as NON_IRAP_NUT. Reference picture list: A list of reference pictures used for inter prediction of P or B slices. Two reference picture lists: reference picture list 0 and reference picture list 1 are generated for each slice of a non-IRAP picture. The set of unique pictures is referenced by all entries of the two reference picture lists associated with the picture consisting of all reference pictures that can be used for inter prediction of the associated picture or any picture following the related picture in decoding order. In order to decode the slice data of the P slice, only the reference picture list 0 is used for inter prediction. To decode the slice data of the B slice, two reference picture lists are used for inter prediction. In order to decode the slice data of the I slice, the reference picture list is not used for inter prediction. Long-term reference image (LTRP): An image marked as "used for long-term reference". Short-term reference image (STRP): An image marked as "used for short-term reference".

The terms "used for short-term reference", "used for long-term reference" or "not used for reference" are defined in section 8.3.3 in VVC in the decoding process for image marking, see section 8.3 in HEVC. 2 Defined in the decoding process for the reference picture set, and in section 7.4.3.3 decoded reference picture marking semantics in AVC. As used herein, these terms have the same meaning.

Related syntax and semantics for the first embodiment are provided below.

NAL unit header syntax.

Sequence parameter set Raw Byte Sequence Payload (RBSP) syntax.

Picture parameter set RBSP syntax

Slice header syntax.

Reference image list structure syntax

NAL unit header semantics.

forbidden_zero_bit must be equal to 0. nal_unit_type designates the type of the RBSP data structure included in the NAL unit.

[Table 7-1] NAL unit type code and NAL unit type class

nuh_temporal_id_plus1 minus 1 designates a time identifier for the NAL unit. The value of nuh_temporal_id_plus1 should not be equal to 0. The TemporalId variable is specified as follows: TemporalId = nuh_temporal_id_plus1　-　1.When nal_unit_type is equal to IRAP_NUT, the coded slice belongs to both IRAP and TemporalId must be equal to 0. The value of TemporalId must be the same for all VCL NAL units of the access unit. The TemporalId value of the coded picture or access unit is the TemporalId value of the VCL NAL unit of the coded picture or access unit. The TemporalId value of a non-VCL NAL unit is limited as follows: If nal_unit_type is equal to SPS_NUT, TemporalId is 0 and TemporalId of the access unit containing the NAL unit must be 0. Otherwise, if nal_unit_type is equal to EOS_NUT or EOB_NUT, TemporalId must be equal to 0. Otherwise, the TemporalId must be greater than or equal to the TemporalId of the access unit containing the NAL unit. When the NAL unit is a non-VCL NAL unit, the value of TemporalId is the same as the minimum value of TemporalId values of all access units to which the non-VCL NAL unit is applied. When nal_unit_type is equal to PPS_NUT, TemporalId may be greater than or equal to TemporalId of the containing access unit, since all image parameter sets (PPS) may be included at the beginning of the bitstream, where the first coded image is equal to 0. It has a TemporalId. When nal_unit_type is equal to PREFIX_SEI_NUT or SUFFIX_SEI_NUT, TemporalId may be greater than or equal to TemporalId of the containing access unit. In the SEI NAL unit, a bit containing an access unit whose TemporalId value is greater than the TemporalId of the access unit including the SEI NAL unit This is because information applied to a subset of streams can be included. nuh_reserved_zero_7bits must be equal to '0000000'. Other values of nuh_reserved_zero_7bits may be specified by ITU-T|ISO/IEC in the future. The decoder must ignore NAL units whose nuh_reserved_zero_7bits value is not equal to '0000000' (ie, remove and discard from the bitstream).

Sequence parameter set RBSP semantics.

log2_max_pic_order_cnt_lsb_minus4 specifies the value of the variable MaxPicOrderCntLsb used in the decoding process for picture order count as follows: MaxPicOrderCntLsb = 2 (log2_max_pic_order_cnt_lsb_minus4 + 4). The value of log2_max_pic_order_cnt_lsb_minus4 must be in the range of 0 to 12 (inclusive). sps_max_dec_pic_buffering_minus1 plus 1 designates the maximum size of a decoded video buffer required for CVS in video storage buffer units. The value of sps_max_dec_pic_buffering_minus1 must be in the range of 0 to MaxDpbSize-1 (inclusive), where MaxDpbSize is the same as specified elsewhere. long_term_ref_pics_flag equal to 0 specifies that LTRP is not used for inter prediction of an arbitrary coded image in CVS. long_term_ref_pics_flag equal to 1 specifies that LTRP can be used for inter prediction of one or more coded images in CVS. additional_lt_poc_lsb specifies the value of the variable MaxLtPicOrderCntLsb used in the decoding process of the reference video list as follows: MaxLtPicOrderCntLsb = 2 (log2_max_pic_order_cnt_lsb_minus4 + 4 + additional_lt_poc_lsb). The value of additional_lt_poc_lsb must be in the range of 0 to 32-log2_max_pic_order_cnt_lsb_minus4-4 (inclusive). If not present, the value of additional_lt_poc_lsb is inferred to be equal to 0. num_ref_pic_lists_in_sps[i] designates the number of ref_pic_list_struct (listIdx, rplsIdx, ltrpFlag) syntax structures having the same listIdx as i included in the SPS. The value of num_ref_pic_lists_in_sps[i] must be in the range of 0 to 64 (inclusive). For each value of listIdx ( equal to 0 or 1), one ref_pic_list_struct(listIdx, rplsIdx, ltrpFlag) syntax structure is signaled directly from the slice header of the current video, so the decoder uses num_ref_pic_lists_in_sps[i] + 1 ref_pic_list_struct(listIdx, rplsIdx, ltrpFlag) Memory must be allocated for the total number of syntax structures.

Image parameter set RBSP semantics.

num_ref_idx_default_active_minus1[i] plus 1 specifies the inferred value of NumRefIdxActive[0] for a P or B slice with num_ref_idx_active_override_flag equal to 0 when i is 0, and when i is 1, num_ref_idx_active_override_flag equal to 0 Specifies the inferred value of NumRefIdxActive[1] for the B slice with. The value of num_ref_idx_default_active_minus1[i] must be in the range of 0 to 14 (inclusive).

Slice header semantics.

If present, the values of each of the slice header syntax elements slice_pic_parameter_set_id and slice_pic_order_cnt_lsb must be the same in all slice headers of the coded image. ... slice_type designates the coding type of the slice according to Table 7-3.

[Table 7-3] Name correlation relationship for slice_type

When nal_unit_type is equal to IRAP_NUT, that is, when the image is an IRAP image, slice_type must be equal to 2. ... slice_pic_order_cnt_lsb designates MaxPicOrderCntLsb as a modulo of the image order count for the current image. The length of the slice_pic_order_cnt_lsb syntax element is log2_max_pic_order_cnt_lsb_minus4 + 4 bits. The value of slice_pic_order_cnt_lsb must be in the range of 0 to MaxPicOrderCntLsb-1 (inclusive). If there is no slice_pic_order_cnt_lsb, slice_pic_order_cnt_lsb is inferred to be equal to 0. ref_pic_list_sps_flag[i] equal to 1 specifies that the reference video list i of the current video is derived based on one of the syntax structures of ref_pic_list_struct (listIdx, rplsIdx, ltrpFlag) whose listIdx is i in the active SPS. ref_pic_list_sps_flag[i] equal to 0 specifies that the reference picture list i of the current picture is derived based on the syntax structure of ref_pic_list_struct(listIdx, rplsIdx, ltrpFlag) in which listIdx directly included in the slice header of the current picture is i. When num_ref_pic_lists_in_sps[i] is 0, the value of ref_pic_list_sps_flag[i] must be equal to 0. ref_pic_list_idx[i] is an index, ref_pic_list_struct (listIdx, rplsIdx, ltrpFlag) syntax structure in which the listIdx used to derive the reference video list i of the current video is the same as i ref_pic_list_struct (listIdx) in the syntax structure, and the listIdx included in the active SPS is i , rplsIdx, ltrpFlag) is specified in a list of syntax structures. The syntax element ref_pic_list_idx[i] is represented by Ceil(Log2(num_ref_pic_lists_in_sps[i] )) bits. If not present, the value of ref_pic_list_idx[i] is deduced as 0. The value of ref_pic_list_idx[i] must be in the range of 0 to num_ref_pic_lists_in_sps[i]-1 (inclusive). num_ref_idx_active_override_flag equal to 1 specifies that the syntax element num_ref_idx_active_minus1[0] exists in the P and B slices, and the syntax element num_ref_idx_active_minus1[1] exists in the B slice. num_ref_idx_active_override_flag equal to 0 specifies that the syntax elements num_ref_idx_active_minus1[0] and num_ref_idx_active_minus1[1] do not exist. num_ref_idx_active_minus1[i], if present, specifies the value of the variable NumRefIdxActive[i] as follows: NumRefIdxActive[i] = num_ref_idx_active_minus1[i] + 1. The value of num_ref_idx_active_minus1[i] ranges from 0 to 14 (inclusive). Should be in the range of.

A value of NumRefIdxActive[i]-1 specifies the maximum reference index for the reference picture list i that can be used to decode a slice. When the value of NumRefIdxActive[i] is 0, the reference index for the reference picture list i cannot be used to decode a slice. When i is 0 or 1, when the current slice is a B slice and num_ref_idx_active_override_flag is 0, it is inferred that NumRefIdxActive[i] is equal to num_ref_idx_default_active_minus1[i] + 1. When the current slice is a P slice and num_ref_idx_active_override_flag is 0, NumRefIdxActive[0] is inferred to be equal to num_ref_idx_default_active_minus1[0] + 1. When the current slice is a P slice, NumRefIdxActive[1] is inferred to be equal to 0. When the current slice is an I slice, it is inferred that both NumRefIdxActive[0] and NumRefIdxActive[1] are equal to 0.

Alternatively, if i is 0 or 1, the following applies after the above: rplsIdx1 is ref_pic_list_sps_flag[i]? ref_pic_list_idx[i]: Set the same as num_ref_pic_lists_in_sps[i], and numRpEntries[i] is the same as num_strp_entries[i][rplsIdx1]　+　num_ltrp_entries[i][rplsIdx1]. When NumRefIdxActive[i] is greater than numRpEntries[i], the value of NumRefIdxActive[i] is set equal to numRpEntries[i].

Reference image list structure semantics.

The ref_pic_list_struct(listIdx, rplsIdx, ltrpFlag) syntax structure may exist in the SPS or slice header. Depending on whether the syntax structure is included in the slice header or the SPS, the following applies: If present in the slice header, ref_pic_list_struct(listIdx, rplsIdx, ltrpFlag) syntax structure is the reference picture list listIdx of the current picture (picture including the slice). Specify Otherwise (exists in SPS), the syntax structure ref_pic_list_struct(listIdx, rplsIdx, ltrpFlag) specifies a candidate for the reference picture list listIdx, and the term "current picture" in the semantics specified in the rest of this section is 1) There is one or more slices including ref_pic_list_idx[listIdx] which is the same as the index for the list of the syntax structure ref_pic_list_struct(listIdx, rplsIdx, ltrpFlag) included in the SPS, and 2) it points to each image in the CVS with the SPS, which is the active SPS. . num_strp_entries[listIdx][rplsIdx] designates the number of STRP entries in the syntax structure ref_pic_list_struct(listIdx, rplsIdx, ltrpFlag). num_ltrp_entries[listIdx][rplsIdx] designates the number of LTRP entries in the syntax structure ref_pic_list_struct(listIdx, rplsIdx, ltrpFlag). If not present, it is inferred that the value of num_ltrp_entries[listIdx][rplsIdx] is equal to 0. The variable NumEntriesInList[listIdx][rplsIdx] is derived as follows: NumEntriesInList[listIdx][rplsIdx] = num_strp_entries[listIdx][rplsIdx] + num_ltrp_entries[listIdx] [rplsIdx]. The value of NumEntriesInList[listIdx][rplsIdx] must be in the range of 0 to sps_max_dec_pic_buffering_minus1 (inclusive). lt_ref_pic_flag[listIdx][rplsIdx][i] equal to 1 designates that the i-th entry of the ref_pic_list_struct(listIdx, rplsIdx, ltrpFlag) syntax structure is an LTRP entry. lt_ref_pic_flag[listIdx][rplsIdx][i] equal to 0 designates that the i-th entry of the ref_pic_list_struct(listIdx, rplsIdx, ltrpFlag) syntax structure is an STRP entry. If it does not exist, it is inferred that the value of lt_ref_pic_flag[listIdx][rplsIdx][i] is equal to 0. The requirement for bitstream conformance is that for all values of i in the range 0 to NumEntriesInList[listIdx][rplsIdx]　-　1 (inclusive), the sum of lt_ref_pic_flag[listIdx][rplsIdx][i] is It should be the same as num_ltrp_entries[listIdx][rplsIdx]. delta_poc_st[listIdx][rplsIdx][i] is the difference between the current picture and the picture order count value of the picture referenced by the i-th entry when the i-th entry is the first STRP entry of the ref_pic_list_struct(rplsIdx, ltrpFlag) syntax structure Or if the i-th entry is an STRP entry but is not the first STRP entry in the ref_pic_list_struct(rplsIdx, 　ltrpFlag) syntax structure, the image referenced by the i-th entry and ref_pic_list_struct(listIdx, 　rplsIdx, 　ltrpFlag) syntax structure transfer Specifies the difference between the image order count values of the images referenced by the STRP. The value of delta_poc_st[listIdx][rplsIdx][i] must be in the range of -215 to 215-1 (inclusive). poc_lsb_lt[listIdx][rplsIdx][i] specifies the value of MaxLtPicOrderCntLsb as an image order count module of the image referenced by the i-th entry of the ref_pic_list_struct(listIdx, 　rplsIdx, 　ltrpFlag) syntax structure. The length of the poc_lsb_lt[listIdx][rplsIdx][i] syntax element is Log2 (MaxLtPicOrderCntLsb) bits.

The decoding process is discussed. The decoding process operates as follows for the current picture CurrPic: The decoding of the NAL unit is specified below. The following process specifies the next decoding process by using the syntax element above the slice header layer. Variables and functions related to the image sequence count are derived. This should only be called for the first slice of the image. At the beginning of the decoding process for each slice of the non-IRAP picture, a decoding process for constructing a reference picture list is called to derive a reference picture list 0 (RefPicList[0]) and a reference picture list 1 (RefPicList[1]). The decoding process for marking the reference picture is called, where the reference picture can be marked as “not used for reference” or “used for long-term reference.” This should only be called for the first slice of the picture. The decoding process is called for tree unit, scaling, transform, in-loop filtering, etc. After all slices of the current picture have been decoded, the currently decoded picture is marked as "used for short-term reference".

The NAL unit decoding process is discussed. The input to this process is the NAL unit of the current picture and the non-VCL NAL unit associated with it. The output of this process is the parsed RBSP syntax structure, encapsulated within the NAL unit. The decoding process for each NAL unit extracts the RBSP syntax structure from the NAL unit and then parses the RBSP syntax structure. The slice decoding process is discussed, including the decoding process for the picture order count. The output of this process is PicOrderCntVal, which is the image order count of the current image. The picture order count is used to identify the picture, for deriving motion parameters and predicting motion vectors, and for checking decoder suitability in the merge mode. Each coded image is associated with an image order count variable denoted by PicOrderCntVal. If the current picture is not an IRAP picture, the variables prevPicOrderCntLsb and prevPicOrderCntMsb are derived as follows: Let prevTid0Pic be the previous picture with TemporalId equal to 0 in decoding order. The variable prevPicOrderCntLsb is set equal to slice_pic_order_cnt_lsb of prevTid0Pic. The prevPicOrderCntMsb variable is set the same as PicOrderCntMsb of prevTid0Pic.

The variable PicOrderCntMsb of the current image is derived as follows: If the current image is an IRAP image, PicOrderCntMsb is set to zero. Otherwise, PicOrderCntMsb is derived as follows:

PicOrderCntVal is derived as follows: PicOrderCntVal = PicOrderCntMsb + slice_pic_order_cnt_lsb.

All IRAP images will have a PicOrderCntVal equal to 0 because slice_pic_order_cnt_lsb is inferred to be 0 for the IRAP image, and both prevPicOrderCntLsb and prevPicOrderCntMsb are set to 0. The value of PicOrderCntVal must be in the range of -231 to 231-1 (inclusive). In one CVS, the PicOrderCntVal values for any two coded images should not be the same.

At any moment during the decoding process, the value of PicOrderCntVal & (MaxLtPicOrderCntLsb-1) for any two reference pictures in the DPB will not be the same. The function PicOrderCnt(picX) is specified as follows: PicOrderCnt(picX) = PicOrderCntVal of image picX. The function DiffPicOrderCnt(picA, picB) is specified as follows: DiffPicOrderCnt(picA, picB) = PicOrderCnt(picA)-PicOrderCnt(picB). The bitstream shall not contain data whose DiffPicOrderCnt(picA, picB) value used in the decoding process does not range from -215 to 215 -1 (inclusive). If X is the current image and Y and Z are the other two images of the same coded video sequence (CVS), Y and Z if both DiffPicOrderCnt(X, Y) and DiffPicOrderCnt(X, Z) are positive or both are negative. Z is considered to be in the same output order direction from X.

The decoding process for building a reference picture list is discussed. This process is called at the beginning of the decoding process for each slice of a non-IRAP picture. The reference image was processed through the reference index. The reference index is an index for the reference video list. When decoding the I slice, the reference picture list is not used for decoding the slice data. When decoding a P slice, only reference picture list 0 (ie, RefPicList[0]) is used for decoding slice data. When decoding the B slice, both reference picture list 0 and reference picture list 1 (ie, RefPicList[1]) are used for decoding slice data. At the beginning of the decoding process for a slice of a non-IRAP picture, reference picture lists RefPicList[0] and RefPicList[1] are derived. The reference picture list is used for marking a reference picture or decoding slice data. In the case of an I slice of a non-IRAP image other than the first slice of an image, RefPicList[0] and RefPicList[1] can be derived for the purpose of checking bitstream conformance, but their derivation is next to the current image in the current image or decoding order. It is not necessary to decode the video coming in. In the case of a P slice other than the first slice of an image, RefPicList[1] may be derived for the purpose of checking bitstream suitability, but this derivation is not necessary for decoding the current image or the image following the current image in decoding order. The reference picture lists RefPicList[0] and RefPicList[1] are constructed as follows:

For each i, which is 0 or 1, the following applies: The first NumRefIdxActive[i] entry in RefPicList[i] is called the active entry in RefPicList[i], and the other entries in RefPicList[i] are RefPicList[i]. Is called an inactive entry. Each entry in RefPicList[i][j] for j in the range 0 to NumEntriesInList[i][RplsIdx[i]]　-　1 (inclusive) has lt_ref_pic_flag[i][RplsIdx[i]][j] If it is 0, it is called an STRP entry, otherwise it is called an LTRP entry. It is also possible for a specific image to be referenced by both the entry of RefPicList[0] and the entry of RefPicList[1]. It is also possible for a specific image to be referenced by one entry of RefPicList[0] or one or more entries of RefPicList[1]. The active entry of RefPicList[0] and the active entry of RefPicList[1] collectively refer to all reference pictures that can be used for inter prediction of the current picture and one or more pictures following the current picture in decoding order. The inactive entry of RefPicList[0] and the inactive entry of RefPicList[1] are not used for inter prediction of the current picture, but collectively refer to all reference pictures that can be used for inter prediction of one or more pictures following the current picture in decoding order. . In RefPicList[0] or RefPicList[1], since a corresponding picture does not exist in the DPB, there may be one or more entries identical to "No Reference Picture". Each of the inactive entries of RefPicList[0] or RefPicList[0] equal to "No Reference Picture" shall be ignored. Unintended picture loss must be inferred for each active entry in RefPicList[0] or RefPicList[1] equal to "No Reference Picture".

The following restrictions apply to the requirements of bitstream conformance: For each i, which is 0 or 1, NumEntriesInList[i][RplsIdx[i]] shall not be less than NumRefIdxActive[i]. The picture referenced by each of the active entries of RefPicList[0] or RefPicList[1] must be in the DPB and must have a TemporalId less than or equal to the TemporalId of the current picture. Optionally, the following constraints may be additionally specified: The entry index of any inactive entry in RefPicList[0] or RefPicList[1] shall not be used as a reference index for decoding of the current picture. Optionally, the following constraints may be additionally specified: An inactive entry in RefPicList[0] or RefPicList[1] must not refer to the same picture as another entry in RefPicList[0] or RefPicList[1]. STRP entries in RefPicList[0] or RefPicList[1] of a slice of an image and LTRP entries in RefPicList[0] or RefPicList[1] of the same slice or different slices of the same image shall not refer to the same image. The current picture itself must not be referenced by any entry in RefPicList[0] or RefPicList[1]. In RefPicList[0] or RefPicList[1], there must not be an LTRP entry with a difference between the PicOrderCntVal of the current video and the PicOrderCntVal of the video referenced by the entry is greater than or equal to 224. Let setOfRefPics be the set of unique images referenced by all entries in RefPicList[0] and all entries in RefPicList[1]. The number of images in setOfRefPics must be less than or equal to sps_max_dec_pic_buffering_minus1, and setOfRefPics must be the same for all slices of the image.

Decoding process for marking reference images.

This process is called once per picture after the decoding process for decoding the slice header and constructing a reference picture list for the slice, but before decoding the slice data. This process may cause one or more reference images in the DPB to be marked as “not used for reference” or “used for long-term reference”. Video decoded in DPB may be marked as "not used for reference", "used for short-term reference" or "used for long-term reference", but at any given time during the operation of the decoding process, one of the three It is marked with only one. If allocating one of these markings to an image is applicable, the other of these markings is implicitly removed. When an image is marked as "used for reference", it is collectively referred to as an image marked as "used for short-term reference" or "used for long-term reference" (but not both). If the current image is an IRAP image, the current All reference images (if any) in the DPB are marked as "not used for reference". STRP is identified by the PicOrderCntVal value. LTRP is identified by the Log2 (MaxLtPicOrderCntLsb) LSB of its PicOrderCntVal value. The following applies: For each of the LTRP entries of RefPicList[0] or RefPicList[1], if the referenced picture is STRP, the picture is marked as "used for long-term reference". Each reference picture of a DPB that is not referenced by any entry in RefPicList[0] or RefPicList[1] is marked as "not used for reference".

A detailed description of a second embodiment of the present disclosure is provided. This section documents the second embodiment of the foregoing disclosure. The description relates to the latest VVC WD. In this embodiment, a set of reference picture list structures is signaled in the SPS, which is shared by reference picture list 0 and reference picture list 1.

Sequence parameter set RBSP syntax.

Picture parameter set RBSP syntax.

Slice header syntax.

Reference image list structure syntax.

The meaning of the NAL unit header is discussed.

Sequence parameter set RBSP semantics.

log2_max_pic_order_cnt_lsb_minus4 specifies the value of the variable MaxPicOrderCntLsb used in the decoding process to count the image order as follows: MaxPicOrderCntLsb = 2 (log2_max_pic_order_cnt_lsb_minus4 + 4). The value of log2_max_pic_order_cnt_lsb_minus4 must be in the range of 0 to 12 (inclusive). sps_max_dec_pic_buffering_minus1 plus 1 designates the maximum size of the decoded video buffer required for CVS in video storage buffer units. The value of sps_max_dec_pic_buffering_minus1 must be in the range of 0 to MaxDpbSize-1 (inclusive), where MaxDpbSize is the same as specified elsewhere. num_ref_pic_lists_in_sps designates the number of ref_pic_list_struct (rplsIdx, ltrpFlag) syntax structures included in the SPS. The value of num_ref_pic_lists_in_sps must be in the range of 0 to 128 (inclusive). Since there may be two ref_pic_list_struct(rplsIdx, ltrpFlag) syntax structures signaled directly from the slice header of the current video, the decoder must allocate memory for the total number of num_short_term_ref_pic_sets　+　2 ref_pic_list_struct(rplsIdx, ltrpFlag) syntax structures. long_term_ref_pics_flag equal to 0 specifies that LTRP is not used for inter prediction of an arbitrary coded image in CVS. long_term_ref_pics_flag equal to 1 specifies that LTRP can be used for inter prediction of one or more coded images in CVS. additional_lt_poc_lsb specifies the value of the variable MaxLtPicOrderCntLsb used in the decoding process for the reference video list as follows: MaxLtPicOrderCntLsb=　2(log2_max_pic_order_cnt_lspoc_minusb4　+　4　_lt_ls). The value of additional_lt_poc_lsb should be in the range of 0 to 32　-　log2_max_pic_order_cnt_lsb_minus4　- 4 (inclusive). If not present, the value of additional_lt_poc_lsb is inferred to be equal to 0.

The picture parameter set RBSP semantics is discussed.

Slice header semantics.

If present, the values of each of the slice header syntax elements slice_pic_parameter_set_id and slice_pic_order_cnt_lsb must be the same in all slice headers of the coded video. slice_type specifies the coding type of a slice according to Table 7-3.

[Table 7-3] Name correlation relationship for slice_type

When nal_unit_type is equal to IRAP_NUT, that is, when the image is an IRAP image, slice_type must be equal to 2. ... slice_pic_order_cnt_lsb designates MaxPicOrderCntLsb as an image order count module for the current image. The length of the slice_pic_order_cnt_lsb syntax element is log2_max_pic_order_cnt_lsb_minus4 + 4 bits. The value of slice_pic_order_cnt_lsb must be in the range of 0 to MaxPicOrderCntLsb-1 (inclusive). If there is no slice_pic_order_cnt_lsb, slice_pic_order_cnt_lsb is inferred to be equal to 0. ref_pic_list_sps_flag[i] equal to 1 specifies that the reference picture list i of the current picture is derived based on one of the syntax structures ref_pic_list_struct(rplsIdx, ltrpFlag) in the active SPS. ref_pic_list_sps_flag[i] equal to 0 specifies that the reference picture list i of the current picture is derived based on the syntax structure ref_pic_list_struct(rplsIdx, ltrpFlag) directly included in the slice header of the current picture. When num_ref_pic_lists_in_sps is 0, the value of ref_pic_list_sps_flag[i] must be equal to 0. ref_pic_list_idx[i] designates an index to a list of the ref_pic_list_struct(rplsIdx, ltrpFlag) syntax structure included in the active SPS of the ref_pic_list_struct(rplsIdx, ltrpFlag) syntax structure used to derive the reference picture list i of the current video. The syntax element ref_pic_list_idx[i] is represented by Ceil(Log2(num_ref_pic_lists_in_sps)) bits. If not present, the value of ref_pic_list_idx[i] is inferred to be equal to 0. The value of ref_pic_list_idx[i] must be in the range of 0 to num_ref_pic_lists_in_sps-1 (inclusive). num_ref_idx_active_override_flag equal to 1 specifies that the syntax element num_ref_idx_active_minus1[0] exists in the P and B slices, and the syntax element num_ref_idx_active_minus1[1] exists in the B slice. num_ref_idx_active_override_flag equal to 0 specifies that the syntax elements num_ref_idx_active_minus1[0] and num_ref_idx_active_minus1[1] do not exist.

num_ref_idx_active_minus1[i], if present, specifies the value of the variable NumRefIdxActive[i] as follows: NumRefIdxActive[i] = num_ref_idx_active_minus1[i] + 1. The value of num_ref_idx_active_minus1[i] ranges from 0 to 14 (inclusive). Should be in the range of. A value of NumRefIdxActive[i]-1 specifies the maximum reference index for the reference picture list i that can be used to decode a slice. When the value of NumRefIdxActive[i] is 0, the reference index for the reference picture list i cannot be used to decode a slice. For each i of 0 or 1, when the current slice is a B slice and num_ref_idx_active_override_flag is 0, NumRefIdxActive[i] is inferred to be equal to num_ref_idx_default_active_minus1[i] + 1. When the current slice is a P slice and num_ref_idx_active_override_flag is 0, NumRefIdxActive[0] is inferred to be equal to num_ref_idx_default_active_minus1[0] + 1. When the current slice is a P slice, NumRefIdxActive[1] is inferred to be equal to 0. When the current slice is an I slice, it is inferred that both NumRefIdxActive[0] and NumRefIdxActive[1] are equal to 0.

Alternatively, for each of i, 0 or 1, the following applies after the above: rplsIdx1 is ref_pic_list_sps_flag[i]? ref_pic_list_idx[i]: It is set the same as num_ref_pic_lists_in_sps[i], and numRpEntries[i] is the same as num_strp_entries[i][rplsIdx1]　+　num_ltrp_entries[i][rplsIdx1]. When NumRefIdxActive[i] is greater than numRpEntries[i], the value of NumRefIdxActive[i] is set equal to numRpEntries[i].

Reference image list structure semantics.

The ref_pic_list_struct(rplsIdx, ltrpFlag) syntax structure may exist in the SPS or slice header. The following applies depending on whether the syntax structure is included in the slice header or the SPS: If present in the slice header, the ref_pic_list_struct(rplsIdx, ltrpFlag) syntax structure specifies the reference picture list of the current picture (picture including the slice). . Otherwise (exists in SPS), the syntax structure ref_pic_list_struct(rplsIdx, ltrpFlag) specifies a candidate reference picture list, and the term "current picture" in the semantics specified in the rest of this section is 1) included in the SPS. There is one or more slices containing ref_pic_list_idx[i] which is the same as the index for the list of the ref_pic_list_struct(rplsIdx, ltrpFlag) syntax structure, and 2) it indicates each image in the CVS having the SPS that is the active SPS. num_strp_entries[rplsIdx] designates the number of STRP entries in the ref_pic_list_struct(rplsIdx, ltrpFlag) syntax structure. num_ltrp_entries[rplsIdx] designates the number of LTRP entries in the syntax structure ref_pic_list_struct(rplsIdx, ltrpFlag). If not present, the value of num_ltrp_entries[rplsIdx] is inferred to be equal to 0.

The variable NumEntriesInList[rplsIdx] is derived as follows: NumEntriesInList[rplsIdx] = num_strp_entries[rplsIdx]　+　num_ltrp_entries[rplsIdx]. The value of NumEntriesInList[rplsIdx] must be in the range of 0 to sps_max_dec_pic_buffering_minus1 (inclusive). lt_ref_pic_flag[rplsIdx][i] equal to 1 designates that the i-th entry of the ref_pic_list_struct(rplsIdx, ltrpFlag) syntax structure is an LTRP entry. lt_ref_pic_flag[rplsIdx][i] equal to 0 designates that the i-th entry of the ref_pic_list_struct(rplsIdx, ltrpFlag) syntax structure is an STRP entry. If not present, the value of lt_ref_pic_flag[rplsIdx][i] is inferred to be equal to 0. The requirement for bitstream conformance is that for all values of i in the range 0 to NumEntriesInList[rplsIdx][rplsIdx][rplsIdx][rplsIdx][rplsIdx][rplsIdx][rplsIdx], the sum of lt_ref_pic_flag[rplsIdx][i]] must equal num_ltrp_entries[rplsIdx]. delta_poc_st[rplsIdx][i], when the i-th entry is the first STRP entry of the ref_pic_list_struct(rplsIdx, ltrpFlag) syntax structure, specifies the difference between the current video and the video order count value of the video referenced by the i-th entry, or , if the i-th entry is an STRP entry but is not the first STRP entry in the ref_pic_list_struct(rplsIdx, ltrpFlag) syntax structure, the image referenced by the i-th entry and ref_pic_list_struct(rplsIdx, ltrpFlag) referenced by the previous STRP in the syntax structure Specifies the difference between the image order count values of the image. The value of delta_poc_st[rplsIdx][i] must be in the range of 0 to 215-1 (inclusive). poc_lsb_lt[rplsIdx][i] is a picture order count module of the picture referenced by the i-th entry of the ref_pic_list_struct(rplsIdx, ltrpFlag) syntax structure, and designates the value of MaxLtPicOrderCntLsb. The length of the poc_lsb_lt[rplsIdx][i] syntax element is Log2 (MaxLtPicOrderCntLsb) bits.

The general decoding process specified as part of the detailed description of the first embodiment of the present disclosure is applied. The NAL unit decoding process will be described. The designated NAL unit decoding process is applied as part of the detailed description of the first embodiment of the present disclosure.

A slice decoding process is provided.

Decoding process for counting the image sequence.

As part of the detailed description of the first embodiment of the present disclosure, the decoding process for the specified picture order count is applied.

Decoding process to build a reference video list.

This process is called at the beginning of the decoding process for each slice of a non-IRAP picture. The reference image is processed through the reference index. The reference index is an index for the reference video list. When decoding the I slice, the reference picture list is not used for decoding the slice data. When decoding a P slice, only reference picture list 0 (ie, RefPicList[0]) is used for decoding slice data. When decoding the B slice, both reference picture list 0 and reference picture list 1 (ie, RefPicList[1]) are used for decoding slice data. At the beginning of the decoding process for a slice of a non-IRAP picture, reference picture lists RefPicList[0] and RefPicList[1] are derived. The reference picture list is used for marking a reference picture or decoding slice data. In the case of an I slice of a non-IRAP image other than the first slice of an image, RefPicList[0] and RefPicList[1] can be derived for the purpose of checking bitstream conformance, but their derivation is next to the current image in the current image or decoding order. It is not necessary to decode the video coming in. In the case of a P slice other than the first slice of an image, RefPicList[1] may be derived for the purpose of checking bitstream suitability, but this derivation is not necessary for decoding the current image or the image following the current image in decoding order. The reference picture lists RefPicList[0] and RefPicList[1] are constructed as follows:

For each i, which is 0 or 1, the following applies: The first NumRefIdxActive[i] entry in RefPicList[i] is called the active entry in RefPicList[i], and the other entries in RefPicList[i] are RefPicList[i]. Is called an inactive entry. Each entry in RefPicList[i][j] for j in the range 0 to NumEntriesInList[RplsIdx[i]]　-　1 (inclusive) is said to be an STRP entry if lt_ref_pic_flag[RplsIdx[i]][j] is 0. Otherwise, it is called an LTRP entry. It is also possible for a specific image to be referenced by both the entry of RefPicList[0] and the entry of RefPicList[1]. It is also possible for a specific image to be referenced by one entry of RefPicList[0] or one or more entries of RefPicList[1]. The active entry of RefPicList[0] and the active entry of RefPicList[1] collectively refer to all reference pictures that can be used for inter prediction of the current picture and one or more pictures following the current picture in decoding order. The inactive entry of RefPicList[0] and the inactive entry of RefPicList[1] are not used for inter prediction of the current picture, but collectively refer to all reference pictures that can be used for inter prediction of one or more pictures following the current picture in decoding order. . In RefPicList[0] or RefPicList[1], since a corresponding picture does not exist in the DPB, there may be one or more entries identical to "No Reference Picture". Each of the inactive entries of RefPicList[0] or RefPicList[0] equal to "No Reference Picture" shall be ignored. Unintended picture loss must be inferred for each active entry in RefPicList[0] or RefPicList[1] equal to "No Reference Picture".

The following restrictions apply to the requirements of bitstream conformance: For each i, which is 0 or 1, NumEntriesInList[RplsIdx[i]] shall not be less than NumRefIdxActive[i]. The picture referenced by each of the active entries of RefPicList[0] or RefPicList[1] must be in the DPB and must have a TemporalId less than or equal to the TemporalId of the current picture. Optionally, the following constraints may be additionally specified: The entry index of any inactive entry in RefPicList[0] or RefPicList[1] shall not be used as a reference index for decoding of the current picture. Optionally, the following constraints may be additionally specified: An inactive entry in RefPicList[0] or RefPicList[1] must not refer to the same picture as another entry in RefPicList[0] or RefPicList[1]. STRP entries in RefPicList[0] or RefPicList[1] of a slice of an image and LTRP entries in RefPicList[0] or RefPicList[1] of the same slice or different slices of the same image shall not refer to the same image. The current picture itself must not be referenced by any entry in RefPicList[0] or RefPicList[1]. In RefPicList[0] or RefPicList[1], there must not be an LTRP entry with a difference between the PicOrderCntVal of the current video and the PicOrderCntVal of the video referenced by the entry is greater than or equal to 224. Let setOfRefPics be the set of unique images referenced by all entries in RefPicList[0] and all entries in RefPicList[1]. The number of images in setOfRefPics must be less than or equal to sps_max_dec_pic_buffering_minus1, and setOfRefPics must be the same for all slices of the image.

The decoding process for marking the reference picture is discussed.

This process is called once per picture after the decoding process for decoding the slice header and constructing a reference picture list for the slice, but before decoding the slice data. This process may cause one or more reference images in the DPB to be marked as “not used for reference” or “used for long-term reference”. Video decoded in DPB may be marked as "not used for reference", "used for short-term reference" or "used for long-term reference", but at any given time during the operation of the decoding process, one of the three It is marked with only one. If allocating one of these markings to an image is applicable, the other of these markings is implicitly removed. When an image is marked as "used for reference", it is collectively referred to as an image marked as "used for short-term reference" or "used for long-term reference" (but not both). If the current image is an IRAP image, the current All reference images (if any) in the DPB are marked as "not used for reference". STRP is identified by the PicOrderCntVal value. LTRP is identified by the Log2 (MaxLtPicOrderCntLsb) LSB of its PicOrderCntVal value.

The following applies: For each of the LTRP entries of RefPicList[0] or RefPicList[1], if the referenced picture is STRP, the picture is marked as "used for long-term reference". Each reference picture of a DPB that is not referenced by any entry in RefPicList[0] or RefPicList[1] is marked as "not used for reference".

5 is an embodiment of a method 500 of decoding a coded video bitstream implemented by a video decoder (eg, video decoder 30). Method 500 may be performed after the decoded bitstream is received directly or indirectly from a video encoder (eg, video encoder 20). Method 500 may be performed to improve the decoding process (eg, to make the decoding process more efficient and faster than a conventional decoding process, etc.). Therefore, it is possible to provide a better user experience by substantially improving the performance of the codec.

At block 502, a set of parameters represented by a coded video bitstream is parsed. In one embodiment, the parameter set comprises a set of syntax elements comprising a reference picture list structure set.

In block 504, the slice header of the current slice represented by the coded video bitstream is parsed. In one embodiment, the slice header includes an index of a reference picture list structure in a set of reference picture list structures in a parameter set.

In block 506, a list of reference pictures of the current slice is derived. In one embodiment, the reference picture list is derived based on the index of the reference picture list structure and the set of syntax elements in the parameter set. In one embodiment, the order of entries in the reference picture list structure is the same as the order of corresponding reference pictures in the reference picture list. In one embodiment, the order is from 0 to the indicated value. In one embodiment, the indicated value is from 0 to the value indicated by sps_max_dec_pic_buffering_minus1.

At block 508, one or more reconstructed blocks of the current slice are obtained. In one embodiment, one or more reconstructed blocks of the current slice are reconstructed based on the reference picture list. After the reconstruction process, the video decoder can output a video or an image. In one embodiment, the video or image may be displayed on a display of an electronic device (eg, a smart phone, tablet, laptop, etc.).

In one embodiment, the reference picture list is designated as RefPictList[0] or RefPictList[1]. In one embodiment, the reference picture list includes a list of reference pictures used for inter prediction. In one embodiment, inter prediction is for a P slice or a B slice. In one embodiment, the set of syntax elements from the parameter set is placed in a raw byte sequence payload (RBSP) of a network abstraction layer (NAL) unit.

A summary of alternative embodiments based on the first and second embodiments is provided.

This section provides a brief summary of other alternative embodiments of the present disclosure. The summary relates to the description of the first embodiment. However, the basic concept of the disclosure for the following alternative embodiment can also be applied to the implementation above the disclosure for the second embodiment. This implementation is the same idea as the way the aspects are implemented over the first embodiment.

Semantics of delta POC of short-term reference image entry.

In one alternative embodiment of the present disclosure, the semantics of a syntax element specifying a delta POC of the i-th entry in the reference picture list structure ref_pic_list_struct() is defined as a POC difference between the current picture and the reference picture associated with the i-th entry. Some of the descriptions used here relate to the current draft standard (e.g. VVC working draft) where only deltas are indicated or described. Removed text is underlined or strikethrough, and added text is highlighted.

The semantics of delta_poc_st[listIdx][rplsIdx][i] are defined as follows: delta_poc_st[listIdx][rplsIdx][i] specifies the difference between the current picture and the picture order count value of the picture referenced by the i-th entry. do. The value of delta_poc_st[listIdx][rplsIdx][i] must be in the range of -215 to 215-1 (inclusive).

The equation of the reference image list construction process needs to be updated. Reference picture lists RefPicList[0] and RefPicList[1] are constructed as follows.

Signaling of long-term reference picture entry.

In one alternative embodiment of the present disclosure, the long-term reference picture entry is not signaled with the same reference picture list structure including the short-term reference picture entry. The long-term reference picture entry is signaled in a separate structure, and for each of the structure entries, there is a syntax element describing the intended position of the long-term reference picture entry to derive a corresponding entry index from the final reference picture list. .

Sequence parameter set RBSP syntax.

Slice header syntax.

Reference image list structure syntax.

Long-term reference image list structure syntax.

Sequence parameter set RBSP semantics.

num_ref_pic_lists_lt_in_sps designates the number of ref_pic_list_lt_struct(ltRplsIdx) syntax structures included in the SPS. The value of num_ref_pic_lists_lt_in_sps must be in the range of 0 to 64 (inclusive). If not present, the value of num_ref_pic_lists_lt_in_sps is inferred to be equal to 0.

Slice header semantics.

ref_pic_list_lt_idx[i] designates an index in the list of the syntax structure ref_pic_list_lt_struct(ltRplsIdx) included in the active SPS used to derive the reference picture list i of the current picture. The syntax element ref_pic_list_lt_idx[i] is represented by Ceil(Log2(num_ref_pic_lists_lt_in_sps)) bits. The value of ref_pic_list_lt_idx must be in the range of 0 to num_ref_pic_lists_lt_in_sps-1 (inclusive).

Reference image list structure semantics.

The ref_pic_list_struct(listIdx, rplsIdx) syntax structure may exist in the SPS or slice header. The following applies depending on whether the syntax structure is included in the slice header or SPS: If it is in the slice header, ref_pic_list_struct(listIdx, rplsIdx) syntax structure specifies the short-term reference picture list listIdx of the current picture (picture including the slice). do. Otherwise (in SPS), the syntax structure ref_pic_list_struct(listIdx, rplsIdx) specifies a candidate for the short-term reference picture list listIdx, and the term "current picture" in the semantics specified in the rest of this section is: 1) SPS There is one or more slices including ref_pic_list_idx[listIdx] that are the same as the index for the list of the ref_pic_list_struct(listIdx, rplsIdx) syntax structure included in the list, and 2) it indicates each image in the CVS having the SPS, which is the active SPS. num_strp_entries[listIdx][rplsIdx] designates the number of STRP entries in the ref_pic_list_struct(listIdx, rplsIdx) syntax structure.

num _ ltrp _entries[ listIdx] [ rplsIdx] Ref_ pic _list_ struct(listIdx , rplsIdx, ltrpFlag ) Syntax Structural LTRP Specify the number of entries. If not present, it is inferred that the value of num_ltrp_entries[listIdx][rplsIdx] is equal to 0.

variable NumEntriesInList[listIdx] [ rplsIdx] Is derived as follows:

NumRefPicEntriesInRpl[listIdx] [ rplsIdx] = num_strp_entries[listIdx][rplsIdx] + num_ltrp_entries[listIdx][rplsIdx] (7-34)

NumRefPicEntries[listIdx] [ rplsIdx] The value of must be in the range of 0 to sps_max_dec_pic_buffering_minus1 (inclusive).

lt _ref_ pic _flag[ listIdx] [ rplsIdx] [i] equal to 1 means ref_pic_list_struct(listIdx, rplsIdx , ltrpFlag ) Syntax The i-th entry of the structure is LTRP Specifies that this is an entry. lt _ref_ pic _flag[ listIdx] [ rplsIdx] [i] equal to 0 is ref_ pic _list_ struct(listIdx , rplsIdx , ltrpFlag) Syntax The i-th entry of the structure is STRP Specifies that this is an entry. If not present, the value of lt_ref_pic_flag[listIdx][rplsIdx][i] is inferred to be equal to 0.

Bitstream The conformance requirement is for all values of i in the range 0 to NumRefPicEntries[listIdx][rplsIdx]　-　1 (inclusive), lt _ref_ pic _flag[ listIdx] [ rplsIdx] The sum of [i] must be equal to num_ltrp_entries[listIdx][rplsIdx].

delta_poc_st[listIdx][rplsIdx][i] is between the current picture and the picture order count value of the picture referenced by the i-th entry when the i-th entry is the first STRP entry of the in ref_pic_list_struct(listIdx, 　rplsIdx) syntax structure. If the difference is specified or the i-th entry is an STRP entry but is not the first STRP entry in the ref_pic_list_struct(rplsIdx, 　ltrpFlag) syntax structure, the image referenced by the i-th entry and the previous STRP of the ref_pic_list_struct(listIdx, 　rplsIdx) syntax structure Specifies the difference between the image order count values of the image referenced by. The value of delta_poc_st[listIdx][rplsIdx][i] must be in the range of -215 to 215-1 (inclusive).

poc _ lsb _ lt[listIdx][rplsIdx][ i] ref_ pic _list_ struct (listIdx,　rplsIdx,　ltrpFlag) Syntax Modulo the picture order count of the picture referenced by the i-th entry in the structure MaxLtPicOrderCntLsb Specify the value. poc_lsb_lt[listIdx][rplsIdx][i] Syntax The length of the element is Log2 (MaxLtPicOrderCntLsb) bits.

Long-term reference image list structure semantics.

The ref_pic_list_lt_struct(ltRplsIdx) syntax structure may exist in the SPS or slice header. Depending on whether the syntax structure is included in the slice header or the SPS, the following applies: If it is in the slice header, the ref_pic_list_lt_struct(ltRplsIdx) syntax structure specifies the long-term reference picture list of the current picture (the picture including the slice), otherwise If not (in SPS), the syntax structure ref_pic_list_struct(listIdx, rplsIdx) specifies a candidate for the long-term reference picture list, and the term "current picture" in the semantics specified in the rest of this section is 1) included in the SPS. One or more slices containing ref_pic_list_lt_idx[i] equal to the index for the list of the ref_pic_list_lt_struct(ltRplsIdx) syntax structured and 2) refer to each image in the CVS with the SPS as the active SPS. num_ltrp_entries[ltRplsIdx] designates the number of LTRP entries in the ref_pic_list_lt_struct(ltRplsIdx) syntax structure. poc_lsb_lt[rplsIdx][i] is a picture order count module of the picture referenced by the i-th entry in the ref_pic_list_lt_struct(rplsIdx) syntax structure, and specifies the value of MaxLtPicOrderCntLsb. The length of the poc_lsb_lt[rplsIdx][i] syntax element is Log2 (MaxLtPicOrderCntLsb) bits. lt_pos_idx[rplsIdx][i] designates the index of the i-th entry in the syntax structure rref_pic_list_lt_struct(rplsIdx) of the reference picture list after construction of the reference picture list. The length of the lt_pos_idx[rplsIdx][i] syntax element is Log2 (sps_max_dec_pic_buffering_minus1　+　1) bits. If num_ltrp_entries[ltRplsIdx] is greater than 1, poc_lsb_lt[rplsIdx][i] and lt_pos_idx[rplsIdx][i] are in descending order of lt_pos_idx[rplsIdx][i] values.

The decoding process is described.

Decoding process to build a reference video list.

This process is called at the beginning of the decoding process for each slice of a non-IRAP picture. The reference image is processed through the reference index. The reference index is an index for the reference video list. When decoding the I slice, the reference picture list is not used for decoding the slice data. When decoding a P slice, only reference picture list 0 (ie, RefPicList[0]) is used for decoding slice data. When decoding the B slice, both reference picture list 0 and reference picture list 1 (ie, RefPicList[1]) are used for decoding slice data. At the beginning of the decoding process for a slice of a non-IRAP picture, reference picture lists RefPicList[0] and RefPicList[1] are derived. The reference picture list is used for marking a reference picture or decoding slice data. In the case of an I slice of a non-IRAP image other than the first slice of an image, RefPicList[0] and RefPicList[1] can be derived for the purpose of checking bitstream conformance, but their derivation is next to the current image in the current image or decoding order. It is not necessary to decode the video coming in. In the case of a P slice other than the first slice of an image, RefPicList[1] may be derived for the purpose of checking bitstream suitability, but this derivation is not necessary for decoding the current image or the image following the current image in decoding order. The reference picture lists RefPicList[0] and RefPicList[1] are constructed as follows:

For each i, which is 0 or 1, the following applies: The first NumRefIdxActive[i] entry in RefPicList[i] is called the active entry in RefPicList[i], and the other entries in RefPicList[i] are RefPicList[i]. Is called an inactive entry. Each entry in RefPicList[i][j] for j in the range 0 to NumEntriesInList[i][RplsIdx[i]]　-　1 (inclusive) has lt_ref_pic_flag[i][RplsIdx[i]][j] If it is 0, it is called an STRP entry, otherwise it is called an LTRP entry. It is also possible for a specific image to be referenced by both the entry of RefPicList[0] and the entry of RefPicList[1]. It is also possible for a specific image to be referenced by one entry of RefPicList[0] or one or more entries of RefPicList[1]. The active entry of RefPicList[0] and the active entry of RefPicList[1] collectively refer to all reference pictures that can be used for inter prediction of the current picture and one or more pictures following the current picture in decoding order. The inactive entry of RefPicList[0] and the inactive entry of RefPicList[1] are not used for inter prediction of the current picture, but collectively refer to all reference pictures that can be used for inter prediction of one or more pictures following the current picture in decoding order. . In RefPicList[0] or RefPicList[1], since a corresponding picture does not exist in the DPB, there may be one or more entries identical to "No Reference Picture". Each of the inactive entries of RefPicList[0] or RefPicList[0] equal to "No Reference Picture" shall be ignored. Unintended picture loss must be inferred for each active entry in RefPicList[0] or RefPicList[1] equal to "No Reference Picture".

Signaling of the number of short-term reference picture entries is discussed.

In one alternative embodiment of the present disclosure, the syntax element specifying the number of entries associated with the short-term reference picture in the reference picture list structure ref_pic_list_struct() is num_strp_entries_minus1[listIdx][rplsIdx] instead of num_strp_entries[listIdx][rplsIdx]. Is defined. This change has two effects on the signaling of the reference picture list: Because the element is coded using ue(v), it is possible to save bits for signaling the number of entries associated with the short-term reference picture in the reference picture list structure. This implicitly restricts each reference picture list to include one or more short-term reference pictures. Some changes to the first embodiment are required to accommodate this idea.

For the reference picture list signaling in the slice header, only the required reference picture list is signaled according to the slice type. That is, one reference picture list for an I or P slice (ie, reference picture list 0) and two reference picture lists for a B slice (ie, both reference picture list 0 and reference picture list 1) are signaled. The slice header syntax is changed as follows:

By applying the above change to the slice header (i.e., reference picture list 0 for I or P slice; reference picture 0 and reference picture 1 for B slice), in the case of P slice, there is only one short-term reference picture. Scheme can be avoided. However, the duplicated short-term reference picture cannot be signaled in the reference picture list 0 and the reference picture list 1, where the entry of the reference picture list 1 is an inactive entry in which the number of active entries of the reference picture list 1 must be equal to 0. The semantics of num_strp_entries_minus1[listIdx][rplsIdx] are changed as follows: num_strp_entries_minus1[listIdx][rplsIdx] plus 1 specifies the number of STRP entries in the ref_pic_list_struct(listIdx, rplsIdx, ltrpFlag) syntax structure. The variable NumEntriesInList[listIdx][rplsIdx] is derived as follows: NumRefPicEntriesInRpl[listIdx][rplsIdx] = num_strp_entries_minus1[listIdx][rplsIdx] + 1 + num_ltrp_entries[listIdx][rplsIdx]. The value of NumRefPicEntries[listIdx][rplsIdx] must be in the range of 1 to sps_max_dec_pic_buffering_minus1 (inclusive).

Allows the inclusion of the current video in the reference video list.

In one alternative embodiment of the present disclosure, the current image may be included in the reference image list. To support this feature, there are no syntax and semantics changes required in connection with the description of the first and second embodiments. However, the bitstream conformance constraint described in the decoding process for constructing a reference picture list must be modified as follows: It is the requirement of bitstream conformance that the following constraint applies: For each i, which is 0 or 1, NumEntriesInList[ i][RplsIdx[i]] must not be less than NumRefIdxActive[i]. The picture referenced by each of the active entries in RefPicList[0] or RefPicList[1] must be in the DPB and must be less than or equal to the TemporalId of the current picture. Optionally, the following constraint may be additionally specified: The entry index of an inactive entry in RefPicList[0] or RefPicList[1] shall not be used as a reference index for decoding the current picture. Optionally, the following constraints can be additionally specified: An inactive entry in RefPicList[0] or RefPicList[1] must not refer to the same picture as another entry in RefPicList[0] or RefPicList[1]. STRP entries in RefPicList[0] or RefPicList[1] of a slice of an image and LTRP entries in RefPicList[0] or RefPicList[1] of the same slice or different slices of the same image shall not refer to the same image. The current picture itself is not referenced by the entry of RefPicList[0] or RefPicList[1]. When the current picture is referenced by an entry in RefPicList[i], for each i of 0 or 1, the entry index must be less than NumRefIdxActive[i]. In RefPicList[0] or RefPicList[1], there must not be an LTRP entry where the difference between the PicOrderCntVal of the current picture and the PicOrderCntVal of the picture referenced by that entry is greater than or equal to 224. Let setOfRefPics be the set of unique images referenced by all entries in RefPicList[0] and all entries in RefPicList[1]. If the current image is not included in setOfRefPics, the number of images in setOfRefPics must be less than or equal to sps_max_dec_pic_buffering_minus1, otherwise the number of images in setOfRefPics must be less than or equal to sps_max_dec_pic_buffering_minus1 + 1. It is the same for all slices of the image.

Different POC LSB bits are used for LTRP entries in the reference picture list.

In one alternative embodiment of the present disclosure, the number of bits used to identify the long-term reference picture in the reference picture list structure may be different between the reference picture list 0 and the reference picture list 1. To support this feature, the following changes are required:

additional_lt_poc_lsb[i] specifies the value of the variable MaxLtPicOrderCntLsb[i] used in the decoding process for the reference picture list listIdx identical to i as follows: MaxLtPicOrderCntLsb[i] = 2 (log2_max_pic_poc_lsb[lsb_minus4 + 4lti] ). The value of additional_lt_poc_lsb[i] must be in the range of 0 to 32-log2_max_pic_order_cnt_lsb_minus4-4 (inclusive). If not present, the value of additional_lt_poc_lsb[i] is estimated to be equal to 0.

poc_lsb_lt[listIdx][rplsIdx][i] is a picture order count module of the picture referenced by the i-th entry in the ref_pic_list_struct(listIdx, rplsIdx, ltrpFlag) syntax structure, and specifies the value of MaxLtPicOrderCntLsb[listIdx]. The length of the poc_lsb_lt[listIdx][rplsIdx][i] syntax element is Log2 (MaxLtPicOrderCntLsb[listIdx]) bits.

Reference picture lists RefPicList[0] and RefPicList[1] are constructed as follows.

Using the same ref_pic_list_sps_flag for reference picture lists 0 and 1.

In one alternative embodiment of the present disclosure, instead of using two flags to indicate whether reference picture list 0 and reference picture list 1 are derived based on the ref_pic_list_struct() syntax structure in the active SPS, one The flag is used for both reference image lists. This alternative is derived based on the ref_pic_list_struct() of the active SPS, or based on the ref_pic_list_struct() syntax structure included directly in the slice header of the current image. The following changes are required to support this feature:

ref_pic_list_sps_flag [i] equal to 1 specifies that the reference picture list i of the current picture is derived based on one of the syntax structures ref_pic_list_struct (listIdx, rplsIdx, ltrpFlag) having the same listIdx as i in the active SPS. ref_pic_list_sps_flag [i] equal to 0 specifies that the reference picture list i of the current picture is derived based on the syntax structure ref_pic_list_struct(listIdx, rplsIdx, ltrpFlag) directly included in the slice header of the current picture. When num_ref_pic_lists_in_sps[0] or num_ref_pic_lists_in_sps[1] is 0, the value of ref_pic_list_sps_flag[i] must be equal to 0. The value of pic_lists_in_sps[1] should be equal to 0, and the value of ref_pic_list_sps_flag should be equal to 0.

Reference picture lists RefPicList[0] and RefPicList[1] are configured as follows.

Signaling of delta POC Most Significant Bit (MSB) for long-term reference image entry.

In one alternative embodiment of the present disclosure, instead of using an additional bit to indicate the POC LSB of the long-term reference picture entry in ref_pic_list_struct(), a POC MSB cycle is signaled to distinguish the long-term reference picture. When signaled, the POC MSB cycle information is signaled for each entry of ref_pic_list_struct() referring to the long-term reference picture. The ref_pic_list_struct() syntax structure is not signaled in the SPS, but only in the slice header. To support this feature, the following changes are required:

The ref_pic_list_struct(listIdx, ltrpFlag) syntax structure may exist in the slice header. When present in the slice header, the ref_pic_list_struct(listIdx, ltrpFlag) syntax structure designates the reference picture list listIdx of the current picture (picture including the slice). num_strp_entries[listIdx] [ rplsIdx ] specifies the number of STRP entries in the syntax structure ref_pic_list_struct(listIdx, rplsIdx , ltrpFlag). num_ltrp_entries[listIdx] [ rplsIdx ] designates the number of LTRP entries in the syntax structure ref_pic_list_struct(listIdx, rplsIdx, ltrpFlag). If not present, the value of num_ltrp_entries[listIdx] [rplsIdx] is estimated to be equal to 0.

The variable NumEntriesInList[listIdx] [ rplsIdx ] is derived as follows:

The value of NumRefPicEntries[listIdx] [ rplsIdx ] must be in the range from 0 to sps_max_dec_pic_buffering_minus1 (inclusive). lt_ref_pic_flag[listIdx][ rplsIdx] [i] equal to 1 designates that the i-th entry of the ref_pic_list_struct(listIdx, rplsIdx, ltrpFlag) syntax structure is an LTRP entry. lt_ref_pic_flag[listIdx][ rplsIdx ] [i] equal to 0 designates that the i-th entry of the ref_pic_list_struct(listIdx, rplsIdx , ltrpFlag) syntax structure is an STRP entry. If not present, the value of lt_ref_pic_flag[listIdx][ rplsIdx ][i] is inferred to be equal to 0. From 0 NumRefPicEntries [listIdx] [rplsIdx] - for all values of i in the range of from 1 (included) lt_ref_pic_flag [listIdx] [rplsIdx] the sum of the [i] num_ltrp_entries [listIdx] [ rplsIdx] and equal to bits This is a requirement for stream conformance. delta_poc_st[listIdx] [ rplsIdx ] [i] is, when the i-th entry is the first STRP entry of the ref_pic_list_struct(listIdx, rplsIdx , ltrpFlag) syntax structure, the picture order count value of the current picture and the picture referenced by the i-th entry specify the difference between, or, i-th entry is TRP entry but ref_pic_list_struct (listIdx, rplsIdx, ltrpFlag), if not the first STRP entry of the syntax structure, ref_pic_list_struct (listIdx, rplsIdx, ltrpFlag) i-th entry and earlier in the syntax structure Specifies the difference between the picture order count values of the picture referenced by the STRP entry. delta_poc_st [listIdx] [rplsIdx] The value of [i] is in the ¹⁵ -2 2 ¹⁵ - should be in the range of from 1 (included). poc_lsb_lt[listIdx] [rplsIdx] [i] is a picture order count module of the picture referenced by the i-th entry in the ref_pic_list_struct(listIdx, rplsIdx, ltrpFlag) syntax structure, and specifies the value of MaxLtPicOrderCntLsb. The length of the syntax element poc_lsb_lt[listIdx][ rplsIdx ][i] is Log2 (Max Lt PicOrderCntLsb) bits. delta_poc_msb_present_flag[listIdx][i] equal to 1 specifies that delta_poc_msb_cycle_lt[listIdx][i] exists. delta_poc_msb_present_flag[listIdx][i] equal to 0 specifies that delta_poc_msb_cycle_lt[listIdx][i] does not exist.

If num_ltrp_entries[listIdx] is greater than 0 and the PicOrderCntVal module MaxPicOrderCntLsb is poc_lsb_lt[listIdx][i] and there is more than one reference picture in the DPG when this slice header is decoded, delta_poc_msb_present_flag[listIdx][i] is equal to 1 It should be the same. If it does not exist, it is inferred that the value of delta_poc_msb_cycle_lt[listIdx][i] is equal to 0. delta_poc_msb_cycle_lt[listIdx][i] is used to determine the value of the most significant bit of the picture order count value of the i-th entry in the ref_pic_list_struct(listIdx, ltrpFlag) syntax structure. If delta_poc_msb_cycle_lt[listIdx][i] does not exist, it is inferred to be equal to 0. Changing the decoding process for the picture order count: At any time during the decoding process, the values of PicOrderCntVal &(MaxLtPicOrderCntLsb-1) for any two reference pictures in the DPB should not be the same.

The reference picture lists RefPicList[0] and RefPicList[1] are constructed as follows:

Alternatively, the semantics of delta_poc_msb_cycle_lt[listIdx][i] can be expressed as a delta of delta so that the reference picture list construction can be updated as follows: Reference picture lists RefPicList[0] and RefPicList[1] are as follows: Is built.

The following restrictions apply to the requirements of bitstream conformance: For each i, which is 0 or 1, NumEntriesInList[i][RplsIdx[i]] shall not be less than NumRefIdxActive[i]. The picture referenced by each of the active entries of RefPicList[0] or RefPicList[1] must be in the DPB and must have a TemporalId less than or equal to the TemporalId of the current picture. Optionally, the following constraints may be additionally specified: The entry index of any inactive entry in RefPicList[0] or RefPicList[1] shall not be used as a reference index for decoding of the current picture. Optionally, the following constraints may be additionally specified: An inactive entry in RefPicList[0] or RefPicList[1] must not refer to the same picture as another entry in RefPicList[0] or RefPicList[1]. STRP entries in RefPicList[0] or RefPicList[1] of a slice of an image and LTRP entries in RefPicList[0] or RefPicList[1] of the same slice or different slices of the same image shall not refer to the same image. The current picture itself must not be referenced by any entry in RefPicList[0] or RefPicList[1]. In RefPicList[0] or RefPicList[1], there must not be an LTRP entry with a difference between the PicOrderCntVal of the current video and the PicOrderCntVal of the video referenced by the entry is greater than or equal to 224. Let setOfRefPics be the set of unique images referenced by all entries in RefPicList[0] and all entries in RefPicList[1]. The number of images in setOfRefPics must be less than or equal to sps_max_dec_pic_buffering_minus1, and setOfRefPics must be the same for all slices of the image.

Each STRP is identified by its PicOrderCntVal value. For each LTRP, if referenced by an entry in RefPicList[0] or RefPicList[1] with delta_poc_msb_present_flag[listIdx][i] equal to 1, it is identified by the PicOrderCntVal value, otherwise Log2(MaxPicOrderCntLsb ) Identified by LSB.

Alternative to signaling of delta POC MSB for long-term reference image entry 1.

This embodiment provides an alternative to the embodiment described in the previous section. Similar to the idea in the previous section, instead of using additional bits to represent the POC LSB of the long-term reference picture in ref_pic_list_struct(), a POC MSB cycle is signaled to distinguish the long-term reference picture. However, in this alternative, when signaled, POC MSB period information is not signaled in ref_pic_list_struct(), but instead, when POC MSB cycle information is required, it is signaled in the slice header. The ref_pic_list_struct() syntax structure may be signaled in the SPS and the slice header.

delta_poc_msb_present_flag[i][j] equal to 1 specifies that delta_poc_msb_cycle_lt[i][j] exists. delta_poc_msb_present_flag[i][j] equal to 0 specifies that delta_poc_msb_cycle_lt[i][j] does not exist. For the jth LTRP entry of the syntax structure ref_pic_list_struct(i, rplsIdx, 1) where NumLtrpEntries[i] is greater than 0, this slice header will be decoded, with MaxPicOrderCntLsb equal to poc_lsb_lt[i] [rplsIdx][jj] with the PicOrderCntVal module. When there is more than one reference picture in the DPB, where jj is the entry index of the entry in the ref_pic_list_struct(i, rplsIdx, 1) syntax structure, which is the j-th LTRP entry in the ref_pic_list_struct(i, rplsIdx, 1) syntax structure, and delta_poc_msb_present_flag[i ] [j] must be equal to 1. If it does not exist, it is inferred that the value of delta_poc_msb_cycle_lt[i] [j] is equal to 0. delta_poc_msb_cycle_lt[i] [j] is used to determine the most significant bit value of the picture order count value of the j-th LTRP entry in the ref_pic_list_struct(i, rplsIdx, 1) syntax structure. If delta_poc_msb_cycle_lt[i] [j] does not exist, it is inferred to be equal to 0.

delta_poc_msb_present_flag[i][j] equal to 1 specifies that delta_poc_msb_cycle_lt[i][j] exists. delta_poc_msb_present_flag[i][j] equal to 0 specifies that delta_poc_msb_cycle_lt[i][j] does not exist. When the slice header with NumLtrpEntries[i] greater than 0 and the PicOrderCntVal module with MaxPicOrderCntLsb poc_lsb_lt[i] [rplsIdx][j] is decoded and there is more than one reference image in DPB, delta_poc_msb_present_flag[i][j] equals 1 and It should be the same. If it does not exist, it is inferred that the value of delta_poc_msb_cycle_lt[i] [j] is equal to 0. delta_poc_msb_cycle_lt[i] [j] is used to determine the value of the most significant bit of the image order count value of the j-th entry in the ref_pic_list_struct(i, rplsIdx, 1) syntax structure. If delta_poc_msb_cycle_lt[i] [j] does not exist, it is inferred to be equal to 0. poc_lsb_lt[listIdx][rplsIdx][i] specifies the value of MaxLtPicOrderCntLsb MaxPicOrderCntLsb as an image order count module of the image referenced by the i-th entry of the ref_pic_list_struct(listIdx, 　rplsIdx, 　ltrpFlag) syntax structure. ref_pic_list_struct(listIdx, rplsIdx, ltrpFlag) -th entry of the syntax structure. The length of the poc_lsb_lt[listIdx][rplsIdx][i] syntax element is Log2 (MaxLtPicOrderCntLsb MaxPicOrderCntLsb) bits.

Changing of the decoding process for a picture sequence count: PicOrderCntVal & (MaxLtPicOrderCntLsb - 1) for the time of the decoding process all, any of the two reference values of the image in the DPB should not be the same.

For slice header design 1, reference picture lists RefPicList[0] and RefPicList[1] are constructed as follows:

Alternatively, in the case of slice header design 1, the semantics of delta_poc_msb_cycle_lt[listIdx][i] can be expressed as delta of delta so that the reference picture list construction can be updated as follows: reference picture list RefPicList[0] and RefPicList [1] is constructed as follows:

In the case of slice header design 2, reference picture lists RefPicList[0] and RefPicList[1] are constructed as follows.

Alternatively, in the case of slice header design 2, the semantics of delta_poc_msb_cycle_lt[listIdx][i] can be expressed as delta of delta so that the reference picture list construction can be updated as follows: reference picture list RefPicList[0] and RefPicList [1] is constructed as follows:

The following restrictions apply to the requirements of bitstream conformance: For each i, which is 0 or 1, NumEntriesInList[i][RplsIdx[i]] shall not be less than NumRefIdxActive[i]. The picture referenced by each of the active entries of RefPicList[0] or RefPicList[1] must be in the DPB and must have a TemporalId less than or equal to the TemporalId of the current picture. Optionally, the following constraints may be additionally specified: The entry index of any inactive entry in RefPicList[0] or RefPicList[1] shall not be used as a reference index for decoding of the current picture. Optionally, the following constraints may be additionally specified: An inactive entry in RefPicList[0] or RefPicList[1] must not refer to the same picture as another entry in RefPicList[0] or RefPicList[1]. STRP entries in RefPicList[0] or RefPicList[1] of a slice of an image and LTRP entries in RefPicList[0] or RefPicList[1] of the same slice or different slices of the same image shall not refer to the same image. The current picture itself must not be referenced by any entry in RefPicList[0] or RefPicList[1]. In RefPicList[0] or RefPicList[1], there must not be an LTRP entry with a difference between the PicOrderCntVal of the current video and the PicOrderCntVal of the video referenced by the entry is greater than or equal to 224. Let setOfRefPics be the set of unique images referenced by all entries in RefPicList[0] and all entries in RefPicList[1]. The number of images in setOfRefPics must be less than or equal to sps_max_dec_pic_buffering_minus1, and setOfRefPics must be the same for all slices of the image.

Each STRP is identified by its PicOrderCntVal value. For each LTRP, if referenced by an entry in RefPicList[0] or RefPicList[1] with delta_poc_msb_present_flag[i] equal to 1, it is identified by the PicOrderCntVal value, otherwise its Log2(MaxPicOrderCntLsb) LSB of its PicOrderCntVal value. Is identified by

Alternative to signaling of delta POC MSB for long-term reference image entry 2.

In one alternative embodiment of the present disclosure, the disclosure described in the first embodiment or the second embodiment can be combined with the above-described embodiment, and “Signaling of delta POC MSB for long-term reference picture entry” and “ It may be named "Alternative 1" of the signaling of delta POC MSB for long-term reference picture entry, respectively. Aspects of the present disclosure to be combined include additional_lt_poc_lsb (i.e., from the first embodiment or the second embodiment) and POC MSB cycle information (i.e., the implementation described above and named "Signaling of delta POC MSB for long-term reference picture entry" Is signaling from the old) and is named "Alternative 1 of signaling of delta POC MSB for long-term reference picture entry" and "signaling of delta POC MSB for long-term reference picture entry". An example of how the above-described first embodiment and the embodiment can be combined and a combination named “Alternative 1 of signaling of delta POC MSB for long-term reference picture entry” can be performed will be described as follows.

delta_poc_msb_present_flag[i][j] equal to 1 specifies that delta_poc_msb_cycle_lt[i][j] exists. delta_poc_msb_present_flag[i][i] equal to 0 specifies that delta_poc_msb_cycle_lt[i][j] does not exist. For the jth LTRP entry in the syntax structure ref_pic_list_struct(i, rplsIdx, 1) where NumLtrpEntries[i] is greater than 0, this slice header will be decoded, with MaxPicOrderLtCntLsb as poc_lsb_lt[i] [rplsIdx][jj] as the PicOrderCntVal module. When there is more than one reference picture in the DPB, where jj is the entry index of the entry in the ref_pic_list_struct(i, rplsIdx, 1) syntax structure, which is the j-th LTRP entry in the ref_pic_list_struct(i, rplsIdx, 1) syntax structure, and delta_poc_msb_present_flag[i ] [j] must be equal to 1. If it does not exist, it is inferred that the value of delta_poc_msb_cycle_lt[i] [j] is equal to 0. delta_poc_msb_cycle_lt[i] [j] is used to determine the most significant bit value of the picture order count value of the j-th LTRP entry in the ref_pic_list_struct(i, rplsIdx, 1) syntax structure. If delta_poc_msb_cycle_lt[i] [j] does not exist, it is inferred to be equal to 0.

Changing the decoding process for the picture order count: At any time during the decoding process, the values of PicOrderCntVal &(MaxLtPicOrderCntLsb-1) for any two reference pictures of the DPB should not be the same.

The reference picture lists RefPicList[0] and RefPicList[1] are constructed as follows:

Alternatively, the semantics of delta_poc_msb_cycle_lt[listIdx][i] can be expressed as a delta of delta so that the reference picture list construction can be updated as follows: Reference picture lists RefPicList[0] and RefPicList[1] are as follows: Is built:

The following restrictions apply to the requirements of bitstream conformance: For each i, which is 0 or 1, NumEntriesInList[i][RplsIdx[i]] shall not be less than NumRefIdxActive[i]. The picture referenced by each of the active entries of RefPicList[0] or RefPicList[1] must be in the DPB and must have a TemporalId less than or equal to the TemporalId of the current picture. Optionally, the following constraints may be additionally specified: The entry index of any inactive entry in RefPicList[0] or RefPicList[1] shall not be used as a reference index for decoding of the current picture. Optionally, the following constraints may be additionally specified: An inactive entry in RefPicList[0] or RefPicList[1] must not refer to the same picture as another entry in RefPicList[0] or RefPicList[1]. STRP entries in RefPicList[0] or RefPicList[1] of a slice of an image and LTRP entries in RefPicList[0] or RefPicList[1] of the same slice or different slices of the same image shall not refer to the same image. The current picture itself must not be referenced by any entry in RefPicList[0] or RefPicList[1]. In RefPicList[0] or RefPicList[1], there must not be an LTRP entry with a difference between the PicOrderCntVal of the current video and the PicOrderCntVal of the video referenced by the entry is greater than or equal to 224. Let setOfRefPics be the set of unique images referenced by all entries in RefPicList[0] and all entries in RefPicList[1]. The number of images in setOfRefPics must be less than or equal to sps_max_dec_pic_buffering_minus1, and setOfRefPics must be the same for all slices of the image.

Each STRP is identified by its PicOrderCntVal value. For each LTRP, if referenced by an entry in RefPicList[0] or RefPicList[1] with delta_poc_msb_present_flag[i] equal to 1, it is identified by the PicOrderCntVal value, otherwise its Log2(MaxLtPicOrderCntLsb) LSB of its PicOrderCntVal value. Is identified by

A reference picture list is signaled in the slice header by always distinguishing short and long-term reference pictures.

This section describes another alternative embodiment of the present disclosure. The description relates to the latest VVC WD (that is, only the delta related to the latest VVC WD of JVET-K1001-v1 is described, the text of the latest VVC WD not mentioned below is applied as it is). This alternative embodiment is summarized as follows: The reference picture list structure is signaled only in the slice header. Both the short-term reference picture and the long-term reference picture are identified by the POC LSB, which can be expressed as a number of bits different from the number of bits used to indicate the POC LSB signaled in the slice header to derive the POC value. In addition, the number of bits used to indicate the POC LSB for identifying the short-term reference picture and the long-term reference picture may be different.

NAL unit header syntax.

Sequence parameter set RBSP syntax.

Picture parameter set RBSP syntax.

Slice header syntax.

Reference image list structure syntax.

NAL unit header semantics.

forbidden_zero_bit must be equal to 0. nal_unit_type designates the type of the RBSP data structure included in the NAL unit.

[Table 7-1] NAL unit type code and NAL unit type class

nuh_temporal_id_plus1 minus 1 designates a time identifier for the NAL unit. The value of nuh_temporal_id_plus1 should not be equal to 0. The variable TemporalId is specified as follows: TemporalId = nuh_temporal_id_plus1-1.

When nal_unit_type is equal to IRAP_NUT, the coded slice belongs to the IRAP image, and the TemporalId must be equal to 0. The value of TemporalId must be the same for all VCL NAL units of the access unit. The TemporalId value of the coded video or access unit is a value of TemporalId of the VCL NAL unit of the coded video or access unit. TemporalId values of non-VCL NAL units are limited as follows: If nal_unit_type is equal to SPS_NUT, TemporalId must be equal to 0 and TemporalId of access unit containing NAL unit must equal 0. Otherwise, if nal_unit_type is equal to EOS_NUT or EOB_NUT, TemporalId must be equal to 0. Otherwise, the TemporalId must be greater than or equal to the TemporalId of the access unit including the NAL unit. When the NAL unit is a non-VCL NAL unit, the value of TemporalId is the same as the minimum value of TemporalId values of all access units to which the non-VCL NAL unit is applied. When nal_unit_type is equal to PPS_NUT, since all image parameter sets (PSS) may be included at the beginning of the bitstream, the TemporalId may be greater than or equal to the TemporalId of the containing access unit, where the first coded image is equal to 0. It has a TemporalId. When nal_unit_type is equal to PREFIX_SEI_NUT or SUFFIX_SEI_NUT, the supplemental enhancement information (SEI) NAL unit may include information applied to a bitstream subunit including an access unit whose TemporalId value is greater than the TemporalId of the access unit including the SEI NAL unit. Therefore, the TemporalId may be greater than or equal to the TemporalId of the containing access unit. nuh_reserved_zero_7bits must be equal to '0000000'. Other values of nuh_reserved_zero_7bits may be specified in the future by ITU-T|ISO/IEC. The decoder must ignore NAL units whose nuh_reserved_zero_7bits value is not equal to '0000000' (ie, remove and discard from the bitstream).

Sequence parameter set RBSP semantics.

log2_max_pic_order_cnt_lsb_minus4 specifies the value of the variable MaxPicOrderCntLsb used in the decoding processor for the picture order count as follows:

MaxPicOrderCntLsb = 2( ^{log2_max_pic_order_cnt_lsb_minus4 + 4)}

The value of log2_max_pic_order_cnt_lsb_minus4 must be in the range of 0 to 12 (inclusive). sps_max_dec_pic_buffering_minus1 plus 1 designates the maximum size of a decoded video buffer required for CVS in video storage buffer units. The value of sps_max_dec_pic_buffering_minus1 must be in the range of 0 to MaxDpbSize-1 (inclusive), where MaxDpbSize is as specified elsewhere. additional_st_poc_lsb specifies the value of the variable MaxStPicOrderCntLsb used in the decoding process for the reference picture list as follows:

MaxStPicOrderCntLsb = 2( ^{log2_max_pic_order_cnt_lsb_minus4 + 4 + additional_st_poc_lsb)}

The value of additional_st_poc_lsb must be in the range of 0 to 32　-　log2_max_pic_order_cnt_lsb_minus4　- 4 (inclusive). long_term_ref_pics_flag equal to 0 specifies that LTRP is not used for inter prediction of an arbitrary coded image in CVS. long_term_ref_pics_flag equal to 1 specifies that LTRP can be used for inter prediction of one or more coded images in CVS. additional_lt_poc_lsb specifies the value of the variable MaxLtPicOrderCntLsb used in the decoding process for the reference picture list as follows:

MaxLtPicOrderCntLsb = 2( ^{log2_max_pic_order_cnt_lsb_minus4 + 4 + additional_st_poc_lsb + additional_lt_poc_lsb)}

Image parameter set RBSP semantics.

num_ref_idx_default_active_minus1[i] plus 1 specifies the inferred value of NumRefIdxActive[0] for a P or B slice with num_ref_idx_active_override_flag equal to 0 when i is 0, and num_ref_idx_active_override_flag equal to 0 when i is 1 Specifies the inferred value of NumRefIdxActive[1] for B slice. The value of num_ref_idx_default_active_minus1[i] must be in the range of 0 to 14 (inclusive).

Slice header semantics.

If present, the values of each of the slice header syntax elements slice_pic_parameter_set_id and slice_pic_order_cnt_lsb must be the same in all slice headers of the coded image. slice_type specifies the coding type of a slice according to Table 7-3.

[Table 7-3] Name correlation relationship for slice_type

When al_unit_type is the same as IRAP_NUT, that is, when the video is an IRAP video, slice_type should be equal to 2.

slice_pic_order_cnt_lsb designates an image order count with the MaxPicOrderCntLsb module for the current image. The length of the slice_pic_order_cnt_lsb syntax element is log2_max_pic_order_cnt_lsb_minus4 + 4 bits. The value of slice_pic_order_cnt_lsb must be in the range of 0 to MaxPicOrderCntLsb-1 (inclusive). If slice_pic_order_cnt_lsb does not exist, slice_pic_order_cnt_lsb is inferred to be equal to 0. num_ref_idx_active_override_flag equal to 1 is,

It is specified that the syntax element num_ref_idx_active_minus1[0] exists for the P and B slices, and that the syntax element num_ref_idx_active_minus1[1] exists for the B slice.

num_ref_idx_active_override_flag equal to 0 specifies that the syntax elements num_ref_idx_active_minus1[0] and num_ref_idx_active_minus1[1] do not exist. When num_ref_idx_active_minus1[i] is present, the value of the variable NumRefIdxActive[i] is designated as follows.

NumRefIdxActive[i] = num_ref_idx_active_minus1[i]　+　1

The value of num_ref_idx_active_minus1[i] must be in the range of 0 to 14 (inclusive). A value of NumRefIdxActive[i]-1 specifies the maximum reference index for the reference picture list i that can be used to decode a slice. When the value of NumRefIdxActive[i] is equal to 0, the slice cannot be decoded using the reference index for the reference picture list i. For each of i, which is 0 or 1, when the current slice is a B slice and num_ref_idx_active_override_flag is equal to 0, NumRefIdxActive[i] is inferred to be equal to num_ref_idx_default_active_minus1[i] + 1. If the current slice is a P slice and num_ref_idx_active_override_flag is equal to 0, NumRefIdxActive[0] is inferred to be equal to num_ref_idx_default_active_minus1[0] + 1. If the current slice is a P slice, it is inferred that NumRefIdxActive[1] is equal to 0. When the current slice is an I slice, it is inferred that both NumRefIdxActive[0] and NumRefIdxActive[1] are equal to 0. Or, for each of i, which is 0 or 1, the following applies after the above is applied: rplsIdx1 to ref_pic_list_sps_flag[i]? ref_pic_list_idx[i]: Set the same as num_ref_pic_lists_in_sps[i], and set numRpEntries[i] the same as num_strp_entries[i][rplsIdx1]　+　num_ltrp_entries[i][rplsIdx1]. When NumRefIdxActive[i] is greater than numRpEntries[i], the value of NumRefIdxActive[i] is set equal to numRpEntries[i].

Reference image list structure semantics.

The ref_pic_list_struct(listIdx, ltrpFlag) syntax structure may exist in the slice header. When present in the slice header, the ref_pic_list_struct(listIdx, ltrpFlag) syntax structure designates the reference picture list listIdx of the current picture (picture including the slice). num_strp_entries[listIdx] designates the number of STRP entries in the ref_pic_list_struct(listIdx, ltrpFlag) syntax structure. num_ltrp_entries[listIdx] designates the number of LTRP entries in the syntax structure ref_pic_list_struct(listIdx, ltrpFlag). If not present, the value of num_ltrp_entries[listIdx] is inferred to be equal to 0. The variable NumEntriesInList[listIdx] is derived as follows:

The value of NumEntriesInList[listIdx] must be in the range of 0 to sps_max_dec_pic_buffering_minus1 (inclusive). lt_ref_pic_flag[listIdx][i] equal to 1 designates that the i-th entry of the ref_pic_list_struct(listIdx, ltrpFlag) syntax structure is an LTRP entry.

lt_ref_pic_flag[listIdx][i] equal to 0 designates that the i-th entry of the ref_pic_list_struct(listIdx, ltrpFlag) syntax structure is an STRP entry. If not present, the value of lt_ref_pic_flag[listIdx][i] is deduced as 0. For all values of i in the range 0 to NumEntriesInList[listIdx]　-　1 (inclusive), the sum of lt_ref_pic_flag[listIdx][i] must equal num_ltrp_entries[listIdx] is a requirement of bitstream conformance.

poc_lsb_st[listIdx][i], when lt_ref_pic_flag[listIdx][i] is 0, designates MaxStPicOrderCntLsb as a picture order count module of the picture referenced by the i-th entry of the ref_pic_list_struct(listIdx, ltrpFlag) syntax. The length of the poc_lsb_st[listIdx][i] syntax element is Log2 (MaxStPicOrderCntLsb) bits. poc_lsb_lt[listIdx][i], when lt_ref_pic_flag[listIdx][i] is 1, designates the value of MaxLtPicOrderCntLsb as a picture order count module of the picture referenced by the i-th entry in the ref_pic_list_struct(listIdx, ltrpFlag) syntax structure. The length of the poc_lsb_lt[listIdx][i] syntax element is Log2 (MaxLtPicOrderCntLsb) bits.

Describe the decoding process.

General decoding process.

The decoding process operates as follows for the current picture CurrPic: The decoding of the NAL unit is specified below. The following process specifies the following decoding process using syntax elements above the slice header layer: Variables and functions related to the picture order count are derived. This should only be called for the first slice of the image. At the beginning of the decoding process for each slice of the non-IRAP picture, the decoding process in which the reference picture list is constructed is called to derive the reference picture list 0 (RefPicList[0]) and the reference picture list 1 (RefPicList[1]). The decoding process for marking the reference picture is called, where the reference picture can be marked as “not used for reference” or “used for long-term reference.” This should only be called for the first slice of the picture. The decoding process is called for tree unit, scaling, transform, in-loop filtering, etc. After all slices of the current picture have been decoded, the currently decoded picture is marked as "used for short-term reference".

NAL unit decoding process.

The input to this process is the NAL unit of the current picture and the associated non-VCL NAL unit. The output of this process is the parsed RBSP syntax structure, encapsulated within the NAL unit. The decoding process for each NAL unit extracts the RBSP syntax structure from the NAL unit and then parses the RBSP syntax structure.

Slice decoding process.

The decoding process for the picture sequence count.

The output of this process is PicOrderCntVal, which is the image order count of the current image. The picture sequence count is used to identify the picture, derive motion parameters from merge mode and motion vector prediction, and check decoder suitability. Each coded picture is associated with a picture order count variable, denoted PicOrderCntVal. If the current picture is not an IRAP picture, the variables prevPicOrderCntLsb and prevPicOrderCntMsb are derived as follows: Let prevTid0Pic be the previous picture with TemporalId of 0 in decoding order. The variable prevPicOrderCntLsb is set equal to slice_pic_order_cnt_lsb of prevTid0Pic. The variable prevPicOrderCntMsb is set the same as PicOrderCntMsb of prevTid0Pic. The variable PicOrderCntMsb of the current image is derived as follows: If the current image is both IRAP, PicOrderCntMsb is set to 0. Otherwise, PicOrderCntMsb is derived as follows.

PicOrderCntVal is derived as follows.

PicOrderCntVal = PicOrderCntMsb + slice_pic_order_cnt_lsb

Since slice_pic_order_cnt_lsb is inferred to be 0 for IRAP images, and prevPicOrderCntLsb and prevPicOrderCntMsb are both set to 0, all IRAP images will have PicOrderCntVal equal to 0. The value of PicOrderCntVal must be in the range of -231 to 231-1 (inclusive). In one CVS, the PicOrderCntVal values for any two coded images should not be the same. At any time during the decoding process, the values of PicOrderCntVal &(MaxStPicOrderCntLsb-1) for any two short-term reference pictures in the DPB should not be the same. At any time during the decoding process, the values of PicOrderCntVal &(MaxLtPicOrderCntLsb-1) for the two reference pictures of the DPB should not be the same.

The function PicOrderCnt(picX) is specified as follows:

PicOrderCnt(picX) = PicOrderCntVal of the picture picX

The function DiffPicOrderCnt(picA, picB) is specified as follows:

Bitstream DiffPicOrderCnt from ^2-215 value of (picA, picB) 2 ¹⁵ to be used in the decoding process - it should not include data that is not in the range of from 1 (included). X is the current image, Y and Z are the other two images in the same CVS, and Y and Z are the same output from X when DiffPicOrderCnt(X, Y) and DiffPicOrderCnt(X, Z) are both positive or negative. It is considered to be in the ordinal direction.

Decoding process to build a reference video list.

This process is called at the beginning of the decoding process for each slice of a non-IRAP picture. The reference image is processed through the reference index. The reference index is an index for the reference video list. When decoding the I slice, the reference picture list is not used for decoding the slice data. When decoding a P slice, only reference picture list 0 (ie, RefPicList[0]) is used for decoding slice data. When decoding the B slice, both reference picture list 0 and reference picture list 1 (ie, RefPicList[1]) are used for decoding slice data. At the beginning of the decoding process for a slice of a non-IRAP picture, reference picture lists RefPicList[0] and RefPicList[1] are derived. The reference picture list is used for marking a reference picture or decoding slice data. In the case of an I slice of a non-IRAP image other than the first slice of an image, RefPicList[0] and RefPicList[1] can be derived for the purpose of checking bitstream conformance, but their derivation is next to the current image in the current image or decoding order. It is not necessary to decode the video coming in. In the case of a P slice other than the first slice of an image, RefPicList[1] may be derived for the purpose of checking bitstream suitability, but this derivation is not necessary for decoding the current image or the image following the current image in decoding order.

The reference picture lists RefPicList[0] and RefPicList[1] are constructed as follows:

For each i, either 0 or 1, the following applies:

The first NumRefIdxActive[i] entry of RefPicList[i] is said to be an active entry of RefPicList[i], and the other entries of RefPicList[i] are said to be inactive entries of RefPicList[i]. Each entry in RefPicList[i][j] for j in the range 0 to NumEntriesInList[i]　-　1 (inclusive) is called a STRP entry if lt_ref_pic_flag[i][j] is 0, otherwise it is called an LTRP entry. do. It is also possible for a specific image to be referenced by both the entry of RefPicList[0] and the entry of RefPicList[1]. It is also possible for a specific image to be referenced by one entry of RefPicList[0] or one or more entries of RefPicList[1]. The active entry of RefPicList[0] and the active entry of RefPicList[1] collectively refer to all reference pictures that can be used for inter prediction of the current picture and one or more pictures following the current picture in decoding order. The inactive entry of RefPicList[0] and the inactive entry of RefPicList[1] are not used for inter prediction of the current picture, but collectively refer to all reference pictures that can be used for inter prediction of one or more pictures following the current picture in decoding order. . In RefPicList[0] or RefPicList[1], since a corresponding picture does not exist in the DPB, there may be one or more entries identical to "No Reference Picture". Each of the inactive entries of RefPicList[0] or RefPicList[0] equal to "No Reference Picture" shall be ignored. Unintended picture loss must be inferred for each active entry in RefPicList[0] or RefPicList[1] equal to "No Reference Picture".

The following restrictions apply to the requirements of bitstream conformance: For each i, which is 0 or 1, NumEntriesInList[i] must not be less than NumRefIdxActive[i]. The picture referenced by each of the active entries of RefPicList[0] or RefPicList[1] must be in the DPB and must have a TemporalId less than or equal to the TemporalId of the current picture. Optionally, the following constraints may be additionally specified: The entry index of any inactive entry in RefPicList[0] or RefPicList[1] shall not be used as a reference index for decoding of the current picture. Optionally, the following constraints may be additionally specified: An inactive entry in RefPicList[0] or RefPicList[1] must not refer to the same picture as another entry in RefPicList[0] or RefPicList[1]. STRP entries in RefPicList[0] or RefPicList[1] of a slice of an image and LTRP entries in RefPicList[0] or RefPicList[1] of the same slice or different slices of the same image shall not refer to the same image. The current picture itself must not be referenced by any entry in RefPicList[0] or RefPicList[1]. In RefPicList[0] or RefPicList[1], there must not be an LTRP entry with a difference between the PicOrderCntVal of the current video and the PicOrderCntVal of the video referenced by the entry is greater than or equal to 224. Let setOfRefPics be the set of unique images referenced by all entries in RefPicList[0] and all entries in RefPicList[1]. The number of images in setOfRefPics must be less than or equal to sps_max_dec_pic_buffering_minus1, and setOfRefPics must be the same for all slices of the image.

Decoding process for marking reference images.

This process is called once per picture after the decoding process for decoding the slice header and constructing a reference picture list for the slice, but before decoding the slice data. This process may cause one or more reference images in the DPB to be marked as “not used for reference” or “used for long-term reference”. Video decoded in DPB may be marked as "not used for reference", "used for short-term reference" or "used for long-term reference", but at any given time during the operation of the decoding process, one of the three It is marked with only one. If allocating one of these markings to an image is applicable, the other of these markings is implicitly removed. When an image is marked as "used for reference", it is collectively referred to as an image marked as "used for short-term reference" or "used for long-term reference" (but not both). If the current image is an IRAP image, the current All reference images (if any) in the DPB are marked as "not used for reference". STRP is identified by Log2(MaxStPicOrderCntLsb) and LSB of its PicOrderCntVal value. LTRP is identified by the Log2 (MaxLtPicOrderCntLsb) LSB of its PicOrderCntVal value.

The following applies: For each of the LTRP entries of RefPicList[0] or RefPicList[1], if the referenced picture is STRP, the picture is marked as "used for long-term reference". Each reference picture of a DPB that is not referenced by any entry in RefPicList[0] or RefPicList[1] is marked as "not used for reference".

A reference picture list is always signaled in the slice header without any distinction between the short-term reference picture and the long-term reference picture.

This section describes another alternative embodiment of the present disclosure. The description relates to the latest VVC WD (that is, only the delta related to the latest VVC WD of JVET-K1001-v1 is described, the text of the latest VVC WD not mentioned below is applied as it is). This alternative embodiment is summarized as follows: The reference picture list structure is signaled only in the slice header. There is no distinction between short-term reference images and long-term reference images. All reference pictures are just named reference pictures. The reference picture is identified by its POC LSB, which can be expressed as a number of bits different from the number of bits used to indicate the POC LSB signaled in the slice header for derivation of the POC value.

Abbreviation. The text in clause 4 of the VVC WD applies.

NAL unit header syntax

Sequence parameter set RBSP syntax.

Picture parameter set RBSP syntax.

Slice header syntax.

Reference image list structure syntax.

NAL unit header semantics.

forbidden_zero_bit must be equal to 0. nal_unit_type designates the type of the RBSP data structure included in the NAL unit.

[Table 7-1] NAL unit type code and NAL unit type class

nuh_temporal_id_plus1 minus 1 designates a time identifier for the NAL unit. The value of nuh_temporal_id_plus1 should not be equal to 0. The variable TemporalId is specified as follows.

TemporalId = nuh_temporal_id_plus1　-　1

When nal_unit_type is equal to IRAP_NUT, the coded slice belongs to the IRAP image, and the TemporalId must be equal to 0. The value of TemporalId must be the same for all VCL NAL units of the access unit. The TemporalId value of the coded picture or access unit is the TemporalId value of the VCL NAL unit of the coded picture or access unit. TemporalId values of non-VCL NAL units are limited as follows:

If nal_unit_type is equal to SPS_NUT, TemporalId must be equal to 0, and TemporalId of access unit including NAL unit must be equal to 0. Otherwise, if nal_unit_type is equal to EOS_NUT or EOB_NUT, TemporalId must be equal to 0. Otherwise, the TemporalId must be greater than or equal to the TemporalId of the access unit including the NAL unit. When the NAL unit is a non-VCL NAL unit, the value of TemporalId is the same as the minimum value of TemporalId values of all access units to which the non-VCL NAL unit is applied. When nal_unit_type is equal to PPS_NUT, since all image parameter sets (PSS) may be included at the beginning of the bitstream, the TemporalId may be greater than or equal to the TemporalId of the containing access unit, where the first coded image is equal to 0. It has a TemporalId. When nal_unit_type is equal to PREFIX_SEI_NUT or SUFFIX_SEI_NUT, the SEI NAL unit may contain information applied to the bitstream subunit including the access unit whose TemporalId value is greater than the TemporalId of the access unit including the SEI NAL unit, so TemporalId is included It may be greater than or equal to the TemporalId of the access unit. nuh_reserved_zero_7bits must be equal to '0000000'. Other values of nuh_reserved_zero_7bits may be specified in the future by ITU-T|ISO/IEC. The decoder must ignore NAL units whose nuh_reserved_zero_7bits value is not equal to '0000000' (ie, remove and discard from the bitstream).

Sequence parameter set RBSP semantics.

log2_max_pic_order_cnt_lsb_minus4 specifies the value of the variable MaxPicOrderCntLsb used in the decoding process for the picture order count as follows:

MaxPicOrderCntLsb = 2( ^{log2_max_pic_order_cnt_lsb_minus4 + 4)}

The value of log2_max_pic_order_cnt_lsb_minus4 must be in the range of 0 to 12 (inclusive). sps_max_dec_pic_buffering_minus1 plus 1 designates the maximum size of the decoded video buffer required for CVS in video storage buffer units. The value of sps_max_dec_pic_buffering_minus1 must be in the range of 0 to MaxDpbSize-1 (inclusive), where MaxDpbSize is as specified elsewhere. additional_ref_poc_lsb specifies the value of the variable MaxRefPicOrderCntLsb used in the decoding process for the reference picture list as follows:

MaxRefPicOrderCntLsb = 2( ^{log2_max_pic_order_cnt_lsb_minus4 + 4 + additional_ref_poc_lsb)}

The value of additional_ref_poc_lsb must be in the range of 0 to 32-log2_max_pic_order_cnt_lsb_minus4-4 (inclusive).

Image parameter set RBSP semantics.

num_ref_idx_default_active_minus1[i] plus 1 specifies the inferred value of NumRefIdxActive[0] for a P or B slice with num_ref_idx_active_override_flag equal to 0 when i is 0, and when i is 1, num_ref_idx_active_override_flag equal to 0 Specifies the inferred value of NumRefIdxActive[1] for the B slice having. The value of num_ref_idx_default_active_minus1[i] must be in the range of 0 to 14 (inclusive).

Slice header semantics.

If present, the values of each of the slice header syntax elements slice_pic_parameter_set_id and slice_pic_order_cnt_lsb must be the same in all slice headers of the coded video. ... slice_type designates the coding type of the slice according to Table 7-3.

[Table 7-3] Name correlation relationship for slice_type

When nal_unit_type is the same as IRAP_NUT, that is, when the video is an IRAP video, slice_type should be equal to 2. ... slice_pic_order_cnt_lsb designates MaxPicOrderCntLsb as an image order count module for the current image. The length of the slice_pic_order_cnt_lsb syntax element is log2_max_pic_order_cnt_lsb_minus4 + 4 bits. The value of slice_pic_order_cnt_lsb must be in the range of 0 to MaxPicOrderCntLsb-1 (inclusive). If slice_pic_order_cnt_lsb does not exist, slice_pic_order_cnt_lsb is inferred to be equal to 0. num_ref_idx_active_override_flag equal to 1 specifies that the syntax element num_ref_idx_active_minus1[0] exists in the P and B slices, and the syntax element num_ref_idx_active_minus1[1] exists in the B slice. num_ref_idx_active_override_flag equal to 0 specifies that the syntax elements num_ref_idx_active_minus1[0] and num_ref_idx_active_minus1[1] do not exist. num_ref_idx_active_minus1[i], if present, specifies the value of the variable NumRefIdxActive[i] as follows:

NumRefIdxActive[i] = num_ref_idx_active_minus1[i]　+　1

The value of num_ref_idx_active_minus1[i] must be in the range of 0 to 14 (inclusive). A value of NumRefIdxActive[i]-1 specifies the maximum reference index for the reference picture list i that can be used to decode a slice. When the value of NumRefIdxActive[i] is 0, the reference index for the reference picture list i cannot be used to decode a slice. For each i whose i is 0 or 1, when the current slice is a B slice and num_ref_idx_active_override_flag is 0, NumRefIdxActive[i] is inferred to be equal to num_ref_idx_default_active_minus1[i] + 1. When the current slice is a P slice and num_ref_idx_active_override_flag is 0, NumRefIdxActive[0] is inferred to be equal to num_ref_idx_default_active_minus1[0] + 1. If the current slice is a P slice, it is inferred that NumRefIdxActive[1] is equal to 0. When the current slice is an I slice, it is inferred that both NumRefIdxActive[0] and NumRefIdxActive[1] are equal to 0. Alternatively, for i, which is 0 or 1, the following applies after applying the above: rplsIdx1 to ref_pic_list_sps_flag[i]? ref_pic_list_idx[i]: Set the same as num_ref_pic_lists_in_sps[i], and let numRpEntries[i] be the same as num_strp_entries[i] [rplsIdx1] + num_ltrp_entries[i] [rplsIdx1]. When NumRefIdxActive[i] is greater than numRpEntries[i], the value of NumRefIdxActive[i] is set equal to numRpEntries[i].

Reference image list structure semantics.

The ref_pic_list_struct(listIdx) syntax structure may exist in the slice header. When present in the slice header, the ref_pic_list_struct(listIdx) syntax structure designates the reference picture list listIdx of the current picture (the picture including the slice). num_ref_entries[listIdx] designates the number of entries in the ref_pic_list_struct(listIdx) syntax structure. The variable NumEntriesInList[listIdx] is derived as follows:

NumRefPicEntriesInRpl[listIdx] = num_ref_entries[listIdx]

The value of NumRefPicEntries[listIdx] must be in the range of 0 to sps_max_dec_pic_buffering_minus1 (inclusive). poc_ref_lsb[listIdx][i] is a picture order count module of the picture referenced by the i-th entry in the ref_pic_list_struct(listIdx) syntax structure, and specifies the value of MaxRefPicOrderCntLsb. The length of the poc_ref_lsb[listIdx][i] syntax element is Log2 (MaxRefPicOrderCntLsb) bits.

The decoding process is described.

General decoding process.

The decoding process operates as follows for the current picture CurrPic: The decoding of the NAL unit is specified below. The following process specifies the following decoding process using syntax elements above the slice header layer: Variables and functions related to the picture order count are derived. This should only be called for the first slice of the image. At the beginning of the decoding process for each slice of the non-IRAP picture, the decoding process in which the reference picture list is constructed is called to derive the reference picture list 0 (RefPicList[0]) and the reference picture list 1 (RefPicList[1]). The decoding process for marking the reference picture is called, where the reference picture can be marked as “not used for reference.” This should be called only for the first slice of the picture: Coding Tree Unit, Scaling, Transformation, Loop The decoding process is called for my filtering, etc. After all slices of the current picture have been decoded, the currently decoded picture is marked as "used for reference".

NAL unit decoding process.

The input to this process is the NAL unit of the current picture and the associated non-VCL NAL unit. The output of this process is the parsed RBSP syntax structure, encapsulated within the NAL unit. The decoding process for each NAL unit extracts the RBSP syntax structure from the NAL unit and then parses the RBSP syntax structure.

Slice decoding process.

Decoding process for counting the image sequence.

The output of this process is PicOrderCntVal, which is the image order count of the current image. The picture sequence count is used to identify the picture, derive motion parameters from merge mode and motion vector prediction, and check decoder suitability. Each coded picture is associated with a picture order count variable, denoted PicOrderCntVal. If the current picture is not an IRAP picture, the variables prevPicOrderCntLsb and prevPicOrderCntMsb are derived as follows: Let prevTid0Pic be the previous picture with TemporalId of 0 in decoding order. The variable prevPicOrderCntLsb is set equal to slice_pic_order_cnt_lsb of prevTid0Pic. The variable prevPicOrderCntMsb is set the same as PicOrderCntMsb of prevTid0Pic. The variable PicOrderCntMsb of the current image is derived as follows: If the current image is both IRAP, PicOrderCntMsb is set to 0. Otherwise, PicOrderCntMsb is derived as follows.

PicOrderCntVal is derived as follows:

PicOrderCntVal = PicOrderCntMsb + slice_pic_order_cnt_lsb

Since slice_pic_order_cnt_lsb is inferred to be 0 for IRAP images, and prevPicOrderCntLsb and prevPicOrderCntMsb are both set to 0, all IRAP images will have PicOrderCntVal equal to 0. The value of PicOrderCntVal must be in the range of -231 to 231-1 (inclusive). In one CVS, the PicOrderCntVal values for any two coded images should not be the same. At any time during the decoding process, the values of PicOrderCntVal&　(MaxRefPicOrderCntLsb　-　1) for any two short-term reference pictures in the DPB should not be the same.

The function PicOrderCnt(picX) is specified as follows:

PicOrderCnt(picX) = PicOrderCntVal of the picture picX

The function DiffPicOrderCnt(picA, picB) is specified as follows:

Bitstream DiffPicOrderCnt from ^2-215 value of (picA, picB) 2 ¹⁵ to be used in the decoding process - it should not include data that is not in the range of from 1 (included). X is the current image, Y and Z are the other two images in the same CVS, and Y and Z are the same output from X when DiffPicOrderCnt(X, Y) and DiffPicOrderCnt(X, Z) are both positive or negative. It is considered to be in the ordinal direction.

Decoding process to build a reference video list.

This process is called at the beginning of the decoding process for each slice of a non-IRAP picture. The reference image is processed through the reference index. The reference index is an index for the reference video list. When decoding the I slice, the reference picture list is not used for decoding the slice data. When decoding a P slice, only reference picture list 0 (ie, RefPicList[0]) is used for decoding slice data. When decoding the B slice, both reference picture list 0 and reference picture list 1 (ie, RefPicList[1]) are used for decoding slice data. At the beginning of the decoding process for a slice of a non-IRAP picture, reference picture lists RefPicList[0] and RefPicList[1] are derived. The reference picture list is used for marking a reference picture or decoding slice data. In the case of an I slice of a non-IRAP image other than the first slice of an image, RefPicList[0] and RefPicList[1] can be derived for the purpose of checking bitstream conformance, but their derivation is next to the current image in the current image or decoding order. It is not necessary to decode the video coming in. In the case of a P slice other than the first slice of an image, RefPicList[1] may be derived for the purpose of checking bitstream suitability, but this derivation is not necessary for decoding the current image or the image following the current image in decoding order. The reference picture lists RefPicList[0] and RefPicList[1] are constructed as follows:

For each i, which is 0 or 1, the first NumRefIdxActive[i] entry in RefPicList[i] is called the active entry in RefPicList[i], and the other entries in RefPicList[i] are called inactive entries in RefPicList[i]. . A specific image can be referenced by both the entry of RefPicList[0] and the entry of RefPicList[1]. A specific image may be referenced by two or more entries of RefPicList[0] or two or more entries of RefPicList[1]. The active entry of RefPicList[0] and the active entry of RefPicList[1] collectively refer to the current picture and all reference pictures that can be used for inter prediction of one or more pictures following the current picture in the sequence. The inactive entry of RefPicList[0] and the inactive entry of RefPicList[1] are not used for inter prediction of the current picture, but collectively refer to all reference pictures that can be used for inter prediction of one or more pictures following the current picture in sequence. Each inactive entry in RefPicList[0] or RefPicList[1] equal to "No Reference Picture" shall be ignored. Unintended picture for each active entry in RefPicList[0] or RefPicList[1] equal to "No Reference Picture". The loss must be inferred.

The following restrictions apply to the requirements of bitstream conformance: For each i, which is 0 or 1, NumEntriesInList[i] must not be less than NumRefIdxActive[i]. The picture referenced by each of the active entries of RefPicList[0] or RefPicList[1] must be in the DPB and must have a TemporalId less than or equal to the TemporalId of the current picture. Optionally, the following constraints may be additionally specified: The entry index of any inactive entry in RefPicList[0] or RefPicList[1] shall not be used as a reference index for decoding of the current picture. Optionally, the following constraints may be additionally specified: An inactive entry in RefPicList[0] or RefPicList[1] must not refer to the same picture as another entry in RefPicList[0] or RefPicList[1]. The current picture itself must not be referenced by any entry in RefPicList[0] or RefPicList[1]. In RefPicList[0] or RefPicList[1], there must not be an LTRP entry with a difference between the PicOrderCntVal of the current video and the PicOrderCntVal of the video referenced by the entry is greater than or equal to 224. Let setOfRefPics be the set of unique images referenced by all entries in RefPicList[0] and all entries in RefPicList[1]. The number of images in setOfRefPics must be less than or equal to sps_max_dec_pic_buffering_minus1, and setOfRefPics must be the same for all slices of the image.

Decoding process for marking reference images.

This process is called once per picture after the decoding process for decoding the slice header and constructing a reference picture list for the slice, but before decoding the slice data. This process can cause one or more reference images in the DPB to be marked as "not used for reference". The picture decoded in the DPB may be marked as "not used for reference" or "used for reference", but at any given time during the operation of the decoding process, it is marked with only one of these two. If allocating one of these markings to an image is applicable, the other of these markings is implicitly removed. If the current image is an IRAP image, all reference images (if any) in the current DPB are marked as "not used for reference". The reference picture of the DPB is identified by the Log2 (MaxRefPicOrderCntLsb) LSB of the PicOrderCntVal value. Each of the reference pictures in the DPB not referenced by any entry in RefPicList[0] or RefPicList[1] is marked as "not used for reference".

Another alternative embodiment.

This section describes an alternative embodiment to the above-described approach, named "Always signaling a reference picture list in a slice header having a difference between a short-term reference picture and a long-term reference picture." In this alternative embodiment, in the slice header, the POC MSB cycle can be signaled for each LTRP entry, similar to HEVC or the above-described approach, and the following constraints are removed: At any time during the decoding process, two of the DPBs The values of PicOrderCntVal & (MaxLtPicOrderCntLsb-1) for the reference image should not be the same.

6 is a schematic diagram of a video coding device 600 (eg, video encoder 20 or video decoder 30) according to an embodiment of the present disclosure. The video coding device 600 is suitable for implementing the disclosed embodiments as described herein. The video coding device 600 includes an inlet port 610 and a receiver unit (Rx) 620 for receiving data; A processor, logic unit, or central processing unit (CPU) 630 for processing data; A transmitter unit (Tx) 640 and an egress port 650 for transmitting data; And a memory 660 for storing data. The video coding device 600 is also an opto-electric (optical-electric) coupled to the inlet port 610, the receiver unit 620, the transmitter unit 640 and the outlet port 650 for the outflow or inflow of an optical signal or an electrical signal. Optical-to-electrical (OE) components and electrical-to-optical (EO) components.

The processor 630 is implemented by hardware and software. The processor 630 may be implemented with one or more CPU chips, cores (eg, a multi-core processor), a field programmable gate array (FPGA), an application specific semiconductor (ASIC), and a digital signal processor (DSP). Processor 630 communicates with inlet port 610, receiver unit 620, transmitter unit 640, outlet port 650 and memory 660. The processor 630 includes a coding module 670. The coding module 670 implements the disclosed embodiment described above. For example, the coding module 670 implements, processes, prepares, or provides various networking functions. Thus, the inclusion of the coding module 670 provides a substantial improvement in the functionality of the video coding device 600 and affects the transformation of the video coding device 600 to another state. Alternatively, coding module 670 is implemented as instructions stored in memory 660 and executed by processor 630.

The video coding device 600 may also include an input and/or output (I/O) device 680 for communicating data with a user. The I/O device 680 may include an output device, such as a display for displaying video data and a speaker for outputting audio data. The I/O device 680 may also include an input device such as a keyboard, mouse, trackball, or the like, and/or a corresponding interface for interacting with such an output device.

The memory 660 includes one or more disks, tape drives, and solid state drives and is used as an overflow data storage device to store programs when such programs are selected for execution, and to store instructions and data read during program execution. Can be used to store. The memory 660 may be volatile and/or non-volatile and may be read-only memory (ROM), random access memory (RAM), ternary content-addressable memory, TCAM) and/or static random-access memory (SRAM). .

7 is a schematic diagram of an embodiment of a coding means 700. In an embodiment, the coding means 700 are implemented in a video coding device 702 (eg video encoder 20 or video decoder 30). The video coding device 702 comprises a receiving means 701. The receiving means 701 is configured to receive an image to be encoded or to receive a bitstream to be decoded. The video coding device 702 comprises a transmitting means 707 connected to a receiving means 701. The transmitting means 707 is configured to transmit the bitstream to the decoder or to transmit the decoded image to the display means (eg, one of the I/O devices 680).

The video coding device 702 comprises storage means 703. The storage means 703 is connected to at least one of the receiving means 701 or the transmitting means 707. The storage means 703 are configured to store instructions. The video coding device 702 also comprises processing means 705. The processing means 705 is coupled to the storage means 703. The processing means 705 is configured to execute an instruction stored in the storage means 703 to perform the method disclosed herein.

While several embodiments have been provided in the present disclosure, it should be understood that the disclosed systems and methods may be implemented in many other specific forms without departing from the spirit or scope of the present disclosure. These examples are to be regarded as illustrative rather than limiting, and such intent is not limited to the details provided herein. For example, various elements or components may be combined or integrated into other systems, or specific functions may be omitted or not implemented.

In addition, techniques, systems, subsystems, and methods described and illustrated individually or separately in various embodiments may be combined or integrated with other systems, modules, technologies, or methods without departing from the scope of the present disclosure. Other items shown or discussed as being coupled, directly coupled or communicating with each other may be electrically, mechanically or otherwise indirectly coupled or communicated via some interface, device, or intermediate component. Other examples of changes, substitutions and modifications may be identified by those skilled in the art and may be made without departing from the spirit and scope disclosed herein.

Claims (18)

A method of decoding a coded video bitstream implemented by a video decoder, comprising:
Parsing a parameter set represented by the coded video bitstream, the parameter set comprising a set of syntax elements comprising a set of reference picture list structures;
Parsing a slice header of a current slice represented by the coded video bitstream, the slice header including an index of a reference picture list structure in a set of reference picture list structures in the parameter set;
Deriving a reference picture list of the current slice based on the set of syntax elements in the parameter set and the index of the reference picture list structure; And
Obtaining one or more reconstructed blocks of the current slice based on the reference image list
How to include. The method of claim 1,
The order of entries in the reference picture list structure is the same as the order of corresponding reference pictures in the reference picture list. The method according to any one of claims 1 to 2,
The order of the entries is from 0 to the indicated value. The method of claim 3,
The method, wherein the indicated value is from 0 to the value indicated by sps_max_dec_pic_buffering_minus1. The method according to any one of claims 1 to 4,
The reference picture list is designated as RefPictList[0]. The method according to any one of claims 1 to 4,
The reference picture list is designated as RefPictList[1]. The method according to any one of claims 1 to 6,
Wherein the one or more reconstructed blocks are used to generate an image displayed on a display of an electronic device. The method according to any one of claims 1 to 7,
The reference picture list includes a list of reference pictures used for inter prediction. The method according to any one of claims 1 to 8,
The method of claim 1, wherein the inter prediction is for a P slice or a B slice. The method according to any one of claims 1 to 9,
Wherein the parameter set comprises a sequence parameter set (SPS). The method according to any one of claims 1 to 10,
The set of syntax elements from the parameter set is placed in a Raw Byte Sequence Payload (RBSP) of a Network Abstraction Layer (NAL) unit. The method according to any one of claims 7 to 11,
The reference picture list is designated as RefPictList[0] or RefPictList[1], and the order of entries in the reference picture list structure is the same as the order of corresponding reference pictures in the reference picture list. The method according to any one of claims 1 to 12,
Parsing a parameter set represented by the coded video bitstream, the parameter set comprising a set of syntax elements comprising a set of reference picture list structures;
Obtaining a reference picture list structure represented by the coded video bitstream;
Deriving a first reference picture list of a current slice based on a reference picture list structure-The first reference picture list includes one or more active entries and one or more inactive entries, and the one or more inactive entries are of the current slice. Refers to a reference picture that is not used for inter prediction but is referenced by an active entry in a second reference picture list, and the second reference picture list is a reference picture list of a slice following the current slice in decoding order, or in decoding order It is a reference video list of the video following the current video -; And
The method further comprising obtaining one or more reconstructed blocks of the current slice based on one or more active entries of the first reference picture list. As a decoding device,
A receiver configured to receive a coded video bitstream;
A memory coupled to the receiver and storing instructions; And
A processor coupled to the memory,
The processor executes the command stored in the memory,
Parsing a parameter set represented by the coded video bitstream, the parameter set comprising a set of syntax elements comprising a set of reference picture list structures;
Parsing a slice header of a current slice represented by the coded video bitstream, the slice header including an index of a reference picture list structure in a set of reference picture list structures in the parameter set;
Derive a reference picture list of the current slice based on the set of syntax elements in the parameter set and the index of the reference picture list structure;
Based on the reference image list, configured to obtain one or more reconstructed blocks of the current slice,
Decoding device. The method of claim 14,
And a display configured to display an image based on the one or more reconstructed blocks. As a coding device,
A receiver configured to receive a bitstream to be decoded;
A transmitter coupled to the receiver and configured to transmit a decoded image to a display;
A memory coupled to at least one of the receiver or the transmitter and configured to store instructions; And
A processor coupled to the memory and configured to execute an instruction stored in the memory to perform the method of any one of claims 1 to 13
Coding device comprising a. As a system,
Encoder; And
A decoder in communication with the encoder,
The decoder comprises the decoding device or coding device of any one of claims 14 to 16,
system. As a means for coding,
Receiving means configured to receive a bitstream to be decoded;
Transmitting means coupled to the receiving means and configured to transmit the decoded image to the display means;
Storage means coupled to at least one of said receiving means or said transmitting means and configured to store an instruction; And
Processing means coupled to said storage means and configured to execute an instruction stored in said storage means to perform the method in any one of claims 1 to 13
Means for coding comprising a.

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